Firefox’s free VPN will offer 50 gigabytes of monthly data, which is pretty generous for a browser-based VPN. A Mozilla account is required to make use of it, which isn’t a hardship (they’re free), but is a point of friction some may wish to know upfront.
We had a proxy server at work that would route all internet traffic and scan for viruses, blocked urls or other traffic patterns, depending on your network rules. It did work on https and SSL traffic, because you had to accept the cert from the proxy server in your browser. So your traffic was encrypted between proxy and webserver, and proxy and your computer, but unencrypted on the proxy server itself. It would be similar with a VPN. Plus, if you control the browser you could just ship the required certs with the update…