MacBook stuck on boot screen, keyboard probably not working correctly

Upon installing an update on my MacBook Pro, after it restarted it did not load and it is stuck on Apple logo and progress bar.

I have tried to boot it up on Diagnostics (holding D key), to boot safe mode (with Shift key), tried CMD+R too - they all result in the same boot stuck (Apple logo + progress bar)

I believe my internal macbook keyboard is not working correctly - either some buttons failed (they are not working or are indicated as pressed all the time) or the whole keyboard is not working - I had some problems with the keyboard before the update.

When booting with Command + R, the loading screen showed a countdown (same Apple logo and progress bar, but with “About 26 minutes remaining”), so I believe the keyboard may work.

I waited a lot and none of the tries to boot the MacBook in any mode worked. It it just stuck on loading screen.

I do not want to give it to a repair center, since in my country there is no Apple Store, I have some confidential info on my MacBook and I definitely do not trust the “official service providers”.

Give me some ideas - how can I make it boot and understand what is the problem.

Is there a way I can boot something from an USB port? I can boot windows, but maybe looking for something smaller, just for diagnostics.

Will an external keyboard work, so I can press the keys combo (D,Command + R, Shift etc) on the external keyboard that is connected via USB? I’m not sure if an external keyboard would work before macOS boots.