I forked this forum and made adjustments so it works with PHP 8. I also added a very simple search page. There are very few changes -- the code is as original Kroc as possible. Besides adding search, I added a few lines to the theme's CSS file, removed the html5 shim, and removed some JavaScript related to iOS orientation which shouldn't be needed anymore.

Github:
https://github.com/zerosonesfun/NoNonsenseForum

My Forum:
https://wilcosky.com/forum/what-is-wilcosky-forum

Search Example:
https://wilcosky.com/forum/search.php?query=forum

Caveats:
- I have no idea if the search will work with a forum that has a ton of feeds. I'm sure it'll get slow/bad unless I continue to develop it. This is a proof of concept only so far.

- I may or may not continue to make adjustments, but my changes could at least help someone running PHP 8 get up and running with this forum software faster -- you could always add back the Google search form if you prefer.