Both Figma autolayout and HStack / VStack are careful subsets of flexbox; not quite the same thing. Consider whether a marble statue is "just a subset" of the block that contained it.

None of these is a perfect technology, but I believe the most practical answer to the question driving this thread[0] is to study/understand the landscape, then build towards a better future.[1]

[0] > Care to point us to a better combination than HTML/CSS when it comes to layouting flexible interfaces?

[1] www.pax.dev