Lukas
Orbot works fine for accessing the onion services (I assume), sure. But Vanadium is not designed with onion services in mind, so I doubt they're going to detect and utilise the onion Brave search as a search engine.
I also don't care about fingerprinting protections that Tor Browser offers.
Not sure why you'd use Tor just to take a risk like this (and not use it to its fullest extent). But you do you I guess.