Wiby is a search engine "for the classic web" which mostly returns simple textual websites. Here's an example, results for 6502, which includes some sites I haven't seen before:
https://wiby.me/?q=6502

Thinking about it, as and when people are building huge and ambitious computers here, and wondering about browsers, one of the obstacles is that the whole encryption thing is quite complex. So having access to an http-only web would be handy. But there's not a great deal of that - it's a pity wiby (linked above) only offers an https version. Likewise, textise.net is quite handy for turning modern sites into text, but it's https-only.

Here are a couple of sites I found - would be interested to hear of others, especially if there's an http-only search engine. Or a big curated directory, as we briefly had before search engines.
http://retro.hackaday.com/
http://textfiles.com/

Oh, here's a search site for vintage-computing purposes, which allows plain http access:
http://frogfind.com/?q=6502

Another candidate for unearthing old-school websites:
https://search.marginalia.nu/

Slightly drifting from the topic, here's an interesting kind of search engine which returns results from discussions - give it 10 or 15 seconds to construct its full response.
https://crew-rho.vercel.app/search?q=65 ... iplication
https://crew-rho.vercel.app/search?q=commodore+pet

And here's a search engine you have to sign up for - I think the idea is that they are motivated to produce the results you want rather than motivated to serve you adverts. They have a few demonstration searches, such as
https://kagi.com/search?q=python+exceptions
https://kagi.com/search?q=steve+jobs

It's probably been mentioned before, but there are text-only browsers in the *nix world. Two that come to mind are lynx and links. Maybe neither of these are of any use for the aforementioned homebuilt projects, but might be worth investigating. I use links only occasionally but, it seems to render https sites pretty well.