Or you can start them pointing to a completely different user-profile-directory.

I do that, no chance for one to leak into the others.

Or you can just use FF containers - which is 99% less work.

Yea, but those came about after I'd built the wrapper for quickly launching different profiles of either Chrome or FF.

FF containers are more work than the 2 clicks I do now, powered by some Python I wrote like 15 years ago (with minor maintenance).

you still have to switch through browser windows right? with containers it is just a tab click and you can put related tabs for a particular topic in a single window

that works to some of the same things firefox can do, but you can also tell firefox to "Always open this site in my banking container" and the next time you load it up, from any container, it will switch it the one you prefer. Also, I really love having amazon and facebook on their own containers, to cut down on all the weird advertising stuff I see..

Chrome's support is way more invasive on google sites. Once you "go multi-profile" you are forced on every google site to do the same thing, because of the borderline-illegal tight integration of Chrome with google sites.

For instance, I can't have Youtube Music playing something on one profile while doing a Google Meet on another profile in a different tab (has to be the other profile window). In Firefox it's site-based (and tab-based) but Chrome locks down on any Google site.

Finally it's actually really hard to undo multi-profile in Chrome once you switch to it, I had to throw out all my Chrome profiles to get back to the old, preferred behavior.