verdict :

Don't buy lowcost PSU, even if you save a few bucks you will end in issues in the future, plus you put your whole system at risks (hopefully mine is kinda secure, even if shitty chems inside)

And 550W PSU are way sufficient even for a 300W Vega 64 + any recent AMD/Intel desktop processor (if you don't take theses 16cores stuff ofc, stay around 100W of CPU) as long you take a nice PSU model (like Seasonic's)