We all make our own personal choices, and I don’t mean to belittle yours (you will probably be OK), but personally I’d be more worried about the prolonged effect of the adhesive from the screen saver.
I had a screen protector on my 2018 MacBook Pro for 2 years without any damage. If I had left the screen open, it would have received far more damage from rubbing against the keyboard. Between greasy finger oil and hard keyboard/trackpad surface versus... soft plastic screen protector and adhesive, I think the screen protector has a much lesser chance of damaging the screen. Also there shouldn't be any problem as long as the screen protector is changed regularly.
If the coating is so weak that adhesive can damage it, what makes you think exposing the bare screen is any better?
It might be best to add something like Dbrand skins around the keyboard and trackpad to increase clearance between keyboard and screen, rather than a keyboard or screen cover which will do the opposite.
Tried. Doesn't really make a difference. Short of covering up the entire keyboard and trackpad with a cover cloth like what's been suggested, the chassis is not rigid enough to prevent parts of the screen from touching the keyboard or trackpad area, regardless of what's around them. This issue should have been resolved when Apple made the chassis thicker but I'm sad to see that not much has changed here.