I ended up keeping chrome just for work, and using firefox for personal life.
Then I grabbed Browser Tamer and set up an AHK v2 script that, when I click on and focus any browser window, it executes browser tamer's CLI to update the default browser. Thus I get the behavior of "open links in last used browser", which is the correct browser for whatever link I click 99.9% of the time.
My solution is: The system has a default browser that opens default links. On my work machine I have a different browser where I am for example logged in to my private github account I just never want to open a clicked link there anyway. Copy/pasting 2 times per day is fine.
Edit: found it: it's hidden behind the browser.profiles.enabled setting in about:config