not being too serious on the question, but pondering

are there any european lock compatible smart lock solutions that are actually secure, do not rely on even having a cloud account ideally and work with home assistant or other such flavoured solutions

switchbot relies on the cloud for even getting a locally valid key, which uh, if we see the implementation right, means that they can provide that key to anyone.....

is there anything actually secure?

@helle Place I rented years ago had something like this. Antenna on the outside to a box that did some RFID. Sent a signal to a solenoid in the door itself. Completely local, and you can just hook up any kind of relay to it. It is however ridiculously expensive.