If someone will get access to my Coinomi wallet on Android 10 they can get access to my private keys? I mean if this someone have understanding of situation and get access full hardware access to my Android 10 smartphone storage.
It's possible but he would need to unlock and break your phone password (if you have it like you should) and break password for your Coinomi wallet, than he could in theory extract your private keys.
Always have good password protection and enable phone encryption in settings, but I would never keep a lot of coins on mobile it should be more as a pocket money.