Not a trainer or physio, but...I think the two most important things are training close to failure and progressive overload. That means 1) the format (bodyweight vs kettlebells vs whatever else) is less important, and 2) always trying to (slowly) progress to more weight/intensity, more volume, etc, rather than something rigid like 20 sets of each exercise indefinitely.
Can you do pull-ups three times a week? If not, two should be alright. Can you get a door frame bar like https://www.amazon.com/gp/product/B07YGMRXMQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1? Or rings could go over strong horizontal beam or tree branch, if there's anything like that closer to your apartment.
I got a same product just that it was rebranded from another reseller, but it seemed sturdy enough and the way the bar is set up you don't have to worry about hitting your head near the door frame.