I have some thoughts on how one might work around these issues. Whilst Facebook will never be usable on an old computer (and some might say that that’s no loss), simpler websites like Wikipedia and the various retro computing interest pages should be viewable if stripped of SSL and, perhaps, stripped of their more modern code.
Email is yet another problem and one that I have made some progress on solving. Using my code (C++, tested on macOS – but it should work on Linux as well) you can now receive email on your vintage computer. It even has (somewhat hacked and messy, I must admit) code to strip emoji.
If you’re interested, if you want to try it, and especially if you want to chip in, you can download it from GitHub here.