Though you won't get stream isolation this way https://www.whonix.org/wiki/Stream_Isolation

Does FF send DNS requests via the proxy? Depending on the personal threat model and the ISP, that might matter.

FF defaults to DNS-over-HTTPS now, so I would imagine it does, although I can't find solid confirmation.

Only in the US.

There are checkboxes to control this in the Firefox proxy settings. "Proxy DNS when using SOCKS v5" and "Enable DNS over HTTPS".

In the proxy options, there's a box to tick for sending DNS through the proxy or not.

Thank you, I'll look in to this!

Be careful doing this though, there's a reason Tor Browser exists and it is because it's very hard to do anonimity over Tor right on a default browser.

Granted, Tor tries to upstream as much as it reasonably can to FF, but there's still large differences in defaults that could give away (some bits of) your identity.

See this comment first, not mine but might as well be https://news.ycombinator.com/item?id=24853678

It's all baby steps. I don't expect to be fully anonymous this way, just like I know my current setup does not foil more sophisticated tracking.