sed -i '' 's|<li class="nav-item p-2">https://www.pgcon.org/|<li class="nav-item p-2">/|g' */index.html

sed -i '' 's|<li class="nav-item p-2">https://www.pgcon.org/events/||g' */index.html

sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||g' */index.html

[14:35 beta dvl /usr/local/www/pgcon.org/2022/content/schedule] % sed -i '' 's|../../../media/css/pgeu.css|media/css/pgeu.css|' index.html
[14:39 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/session] % sed -i '' 's|<li class="nav-item p-2">https://www.pgcon.org/|<li class="nav-item p-2">/|g' */index.html

[14:39 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/session] % sed -i '' 's|li class="nav-item p-2"><a href="https://www.pgcon.org|/|g' */index.html

[14:40 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/session] % sed -i '' 's|<li class="nav-item p-2">https://www.pgcon.org/events/||g' */index.html

[14:43 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/session] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||g' */index.html

[15:16 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/speaker] % sed -i '' 's|../../../../../media/css/pgeu.css|../../media/css/pgeu.css|' */index.html   
[15:17 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/speaker] % sed -i '' 's|img class="speaker-photo" src="../../../../speaker|img class="speaker-photo" src="../|' */index.html
[15:05 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/speaker] % sed -i '' 's|https://www.pgcon.org/" title="Home"|/" title="Home"|' */index.html 

[15:06 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/speaker] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/events/||' */index.html

[15:07 beta dvl /usr/local/www/pgcon.org/2022/content/schedule/speaker] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||' */index.html

The conversion to HTML involves two parts:

* fetch the data
* adjust links

First, fetch the website:

[15:40 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] % wget -m -p -k -r -np --reject-regex='/\/\//' https://www.pgcon.org/events/pgcon_2020/schedule/

Move the index over:

[15:41 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] % mv -i www.pgcon.org/events/pgcon_2020/schedule/index.html .

Move session and speaker information:
[15:38 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/www.pgcon.org/events/pgcon_2020/schedule] % mv session speaker /usr/local/www/pgcon.org/2020/content/schedule

Move speaker photos into the speaker directory:

[15:39 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/www.pgcon.org/events/speaker] % mv * /usr/local/www/pgcon.org/2020/content/schedule/speaker 

At this point, I saved what I had into my repo, so I have a fallback position when updating links.

Now we update the links:

NOTE: your version of sed may not want the '-i ''' option. Perhaps it only needs '-i'

These consists of three areas:

* schedule home directory
* speakers
* sessions

With more fancy sed, you might be able to combine these steps.

Adjust css link
[15:43 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] % sed -i '' 's|../../../media/css/pgeu.css|media/css/pgeu.css|' index.html            

Make the home directory link to the website (be it your beta or production, no need to mention the hostname when it may vary)
[15:43 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] %  sed -i '' 's|li class="nav-item p-2"><a href="https://www.pgcon.org/" title="Home">|li class="nav-item p-2"><a href="/" title="Home">|g' index.html

Remove the link for events
[15:45 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/events/||' index.html

Remove the link for your account
[15:46 beta dvl /usr/local/www/pgcon.org/2020/content/schedule] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||' index.html

Repeat for speakers:

[15:46 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/speaker] % sed -i '' 's|../../../../../media/css/pgeu.css|../../media/css/pgeu.css|' */index.html   
[15:46 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/speaker] % sed -i '' 's|img class="speaker-photo" src="../../../../speaker|img class="speaker-photo" src="../|' */index.html
[15:46 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/speaker] % sed -i '' 's|li class="nav-item p-2"><a href="https://www.pgcon.org/" title="Home">|li class="nav-item p-2"><a href="/" title="Home">|g' */index.html
[15:47 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/speaker] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||' */index.html
[15:47 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/speaker] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/events/||' */index.html

And then for sessions:
[15:49 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/session] % sed -i '' 's|../../../../../media/css/pgeu.css|../../media/css/pgeu.css|' */index.html   
[15:49 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/session] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/events/||' */index.html
[15:49 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/session] %  sed -i '' 's|li class="nav-item p-2"><a href="https://www.pgcon.org/" title="Home">|li class="nav-item p-2"><a href="/" title="Home">|g' */index.html
[15:50 beta dvl /usr/local/www/pgcon.org/2020/content/schedule/session] % sed -i '' 's|                 <li class="nav-item p-2">https://www.pgcon.org/account/||' */index.html

   # handle the conversion from pgeu to static files
   rewrite ^/events/pgcon_2020/schedule/(.*)$ /2020/schedule/$1 permanent;
   rewrite ^/events/pgcon_2021/schedule/(.*)$ /2021/schedule/$1 permanent;
   rewrite ^/events/pgcon_2022/schedule/(.*)$ /2022/schedule/$1 permanent;
   rewrite ^/events/pgcon_2023/schedule/(.*)$ /2023/schedule/$1 permanent;