This is sort-of happening. The UK is making it easier for the Hong-Kongese to relocate to the UK and gain citizenship. Note "easier" doesn't mean "easy", and one needs to get out of HK first, presumably.
But speaking of the UK, it is a massive slap in its face. The UK brokered the unification agreement (not that they had much pragmatic choice but to give up HK), China is now not even pretending to honour it.
A bit like with Ukraine's deal to give up nuclear arms: https://en.wikipedia.org/wiki/Budapest_Memorandum_on_Securit... . I'm amazed this has gone down so placidly.