Sure. I've seen worse.

Yes, that looks fine.
But if you mount it in a chassis you should use something under it to make sure it doesn't short out =)

Tho its quite possible to break something if you bend a mobo ofc.
Large chips and especially BGA's (the ones WO pins on the sides) are sensitive to bending.
The board bends but the chip doesn't, and you put a lot of stress on the solder joints/pins.
There's actually a lot of modern graphics cards that suffer from this, the insane weight of it bends it to much and the memory chips closest to the PCIe connector loses contact.

50/50. More modern board would probably be dead for sure, but Socket 7 usually has less brittle components.

Agree ! old boards can be bent and still work fine. Just do not over tighten when mounting. Be sure to boot the board before you mount it (That is always #1 rule for many of us) to make sure it works.
Seems most of the "newbs" want to mount a board in a case, put all the hardware in and then cry "why does it not work ?" :p

Either was mounted in a way letting it sag, or spend years in storage like this. Dont go trying to straighten it now excessively, make sure its firmly supported on all the mounting holes with optional shims to match the bend.

AT mounting would not cause that amount of sag. Or any at all, really. Sagging became a thing during Socket 478 era and beyond, because cooler mountings were shit. That motherboard was improperly handled during shipment or storage.

Thanks for your answers.
Could I also ask you for some tips about the motherboard model? BIOS chip looks empty.

If I remember correctly, PCChips M537DMA33.
VIA VPX chipset - a bit slow, but from my experience, rock solid. From what I could remember, it should be equivalent to 430VX?

Yep, it does seem to be a M537 looking at the pictures - https://www.ultimateretro.net/en/motherboards/6150 or https://www.ultimateretro.net/en/motherboards/6156
The renaming of the chipset made it a bit awkward to find on UltimateRetro, but I think PC Chips were the only ones doing that, so there's a clue.

Yeah same as Amptron PM-8400.