> You can do DNS over HTTPS through Firefox (sadly not on an OS level in Windows for example, but that's fine -- I'm sure OS level support works better on Linux

I'm using https://github.com/dimkr/nss-tls with https://github.com/dimkr/dohli on Linux and it works well. Everything, not just the browser, uses DoH and with endless customization, since I own the server.