Short Trip to Kaliningrad

Hi as i am based in Switzerland i am travelling to Gdansk this Weekend and want to spend 2 days in Kaliningrad.
I do have Visa for Russia so i do not expect problems.

If i find rental car in Gdansk which allows to take the car to Kalinigrad it will be fine otherwise i will take the bus or maybe an Uber. Does anyone have info on transport means from Gdansk to Kaliningrad and back?

Any suggestions on what you would recommend? I love Food, local atmosphere and maybe some wellness.
Thanks and see you soon