One is indeed able to hide the HUD completely with a command but only a few things can be hidden in game/ through game files. The objectives showing the boss statuses can't be hidden. Absolutely would love them to add a key for that!

I'm pretty sure there are workarounds to being able to hide the HUD elements. Even though a hotkey or the opportunity to bind a key to hide the HUD would be welcome for sure!

You can't, thats the issue unfortunately

I've taken this screenshot a long ago, maybe it was back in 2018-19 when the game released in Early Access.
Back then the boss info only appeared after you've collected your 1st clue if I can recall it correctly.

I think you can hide the HUD elements in the options now though - if you don't wanna see the boss icon at all.

How did you manage to get rid of the boss information on your left?