Yeah it would be nice if wifi direct was in the app itself, but it only uses the network you’re connected to. So if you local send with one phone connected to the other via hotspot (just like wifi direct) then local send will send directly and be faster. When I tried with my laptop and phone it was about 30 MB/s.
Custom ROMs have had this design for a long time already. Interesting that Google also decided to use it. Here’s a screenshot from my custom ROM on A14, just has different groupings.
https://ibb.co/Sx8k6HQ