It may have made sense technically but China has a huge army and HK is dependent on water, electricity and food which comes from the mainland. The mainland government made very clear that if HK wasn't returned, they would cut off the water supply.
It's not stealing from China to not give them something taken from someone else.
UK could have demanded a lease renewal from PRC as the price for switching recognition. Instead they just got some “alliance” against the Soviets and it is questionable what that actually delivered.
Giving HK back to China is an act of decolonization. Putting them under Taiwan and loading up the island with US weapons would not be.
PRC is itself a colonialist power. See all the Uighurs in concentration camps.
I don't want to devalue your experience, but Anglo powers have a terrible record of "colonialism for their own good", "we'll be greeted as liberators", etc.
China doesn't like to take credit for that, but personally I believe its alliance with the West was instrumental in the collapse of the Soviet Union.