You can add a bookmark shortcut button with the address about:profile and that makes it more accessible. I added a key shortcut to the bookmark itself. Then I can use cmd + L to focus the address bar, type the letter p, and hit Enter. That opens the profiles page and it’s reasonably fast.

I also created a similar bookmark with a JavaScript snippet that removes fixed elements from the page, typically top bars. I now have it in my muscle memory.

Until Mozilla disables bookmark keywords on the desktop browser, too (on the android version they have been nuked already).

the portable version is also an option if the user passes a location as the profile path. This can be made more convenient by adding shortcuts for each profile.

The UX could definitely be improved, but it's manageable in my opinion

The "portable version" is not maintained pr built by Mozilla and breaks/disables the sandbox. Don’t use it.