Proof of onward travel requirements

Hi, I’m going to Hong Kong in 12 days and I’m wondering about onward travel requirements. I’ve seen in some places that not having a ticket booked for onward travel could be a problem. I’m from the UK and do not hold any other passport.

My currently plan is to fly into Hong Kong then a few days after to fly to Taipei (not booked yet). I’m not entirely sure how long I’d stay there, but I think I might want to go to mainland China / Vietnam (but again nothing booked). I’d probably want to be in the region for roughly a month. I also haven’t booked a return ticket yet because so don’t really know where I’m going to be.

Could my plan pose problems with no onward travel booked? Thanks