Use an app that makes a Work Profile like Island/Shelter and put the important apps in there. Only issue is that they'll be completely sandboxed from the rest of the system.
How old/smart is your kid? You could just use a launcher that allows you to hide the apps too
I haven't tried these myself but there's MaxLock for a FOSS option that supposedly still works despite being old. Otherwise I've seen AppLock suggested.
Use an app that makes a Work Profile like Island/Shelter and put the important apps in there. Only issue is that they'll be completely sandboxed from the rest of the system.
How old/smart is your kid? You could just use a launcher that allows you to hide the apps too