For my personal setup I’ve been wanting to do it on a VPS I have. I route my traffic through a bundle of VPNs from the US to Switzerland and I end up needing to clear browser cache often (web developer testing JavaScript, etc).

each site hosts their own copy of jQuery or whatever the kids use these days

I do this in my projects (Hotwire) but I wish I could say the same for other websites. I still run into broken websites due to trying to import jQuery from Google for example. This would be another nice thing to have cached.