So far the only 1 I found that works while full-screen for me

If you have issues, I think this addon might not be getting updates.

Suited to my needs (HBO Max). I've had to download the subs manually on opensubtitles.com, and set a delay of -14000 or -29000 depending on the length of the ad before the show. Sometimes the add-on glitches, the solution there is to "remove subtitle" and start again.
Not perfect, but honestly the only solution I found.

Simple and effective. Super useful for movies missing subtitles!

Works perfectly and has a lot of useful features!