Yes, but Firefox's profiles are very hard to use (apart from keeping multiple Firefox channels installed, e.g., stable, beta), I tried, and I couldn't.
Starting a profile is difficult, and also switching between windows, since the OS sees profiles as different apps. It's probably not hard to fix, but Mozilla has had other priorities.
Just open about:profiles. You can create new ones, remove old ones, set which one is the default and can open them in a new browser. I use this all the time to open a browser as a new SSO functional user without having to log out.
I don't know why they don't add this somewhere in the menus and I don't know why you can't bookmark about:profiles, but this works well for me as it is.
The -ProfileManager flag to Firefox gives a startup window to manage, create, and select profiles (and has existed forever).
You can create shortcuts (or shell scripts) by hand with --no-remote -p ProfileName to auto-open specific sites in specific profiles. It's certainly less convenient than PWA installs, but is an old tool with all sorts of old ways to automate it.
Multi-account Container is far easier than all that though and does reduce the number of windows to manage in your OS taskbars. Obviously you need to be careful with which extensions you install that they are safe for every container you want to use, but that's a given and a good idea in general no matter how many profiles you use: keep extensions to the bare minimum you are comfortable with. Vet their permissions manifests and keep additional permissions you grant them to a minimum.
My problem is opening links from apps. Sometimes I want a link in Slack (or other desktop apps) to open in my personal profile and sometimes I want it to use my work profile. With Brave/Chrome, the link will open in whatever profile window is active. I can't find a way to make this work with Firefox.
Starting a profile is difficult, and also switching between windows, since the OS sees profiles as different apps. It's probably not hard to fix, but Mozilla has had other priorities.