Thank you for responding @kingwicked
! My problem behaves the same, except that it doesn't seem to be camera-related, and it hasn't solved itself by now (~4 days). I can see the screen via HDMI and touch the black screen to do anything - calls and all.
One thing I haven't done is updating the phone to the latest firmware - I'm currently on Android 10. I don't want to try updating to 11 right now because I'm worried the current display mirroring setup might get messed up. I'll be blind again if that happens.
I've been quite careful with the phone too. No drops or anything. The phone usually heats up tangibly but I didn't think too much of it since it's a tropical country and the phone has a powerful chipset.
Anyway, I think I'll need to buy another phone for the time being. Repair parts are in short supply and the cost of replacing the display is barely below getting a second-hand S10+