Sony a7R III to the a7R II a7s AF accuracy and speed with third party lenses...?

I am just wondering how fast and accurately the a7R III, to the a7R II an the a7s focus with third part lenses like Canon and Nikon?
Are they usable for wedding? Is there anybody who used these mirrorless cameras for wedding with third party lenses...
Thanks so much!

I've been reading a lot of posts here plus a lot of reviews and examples on Youtube. It's evident people are using a couple of those for weddings professionally and getting some good images. But from what I gather, the A7R iii or A9 make the A7R ii seem like a museum artifact. Apparently native glass is a great option, because there's plenty of honest reviews on Youtube showing inconsistency with 3rd party glass.

I use Canon and considered adding Sony. But Canon, Nikon and Olympus are all so good now, that changing systems is pointless. But from all I read and saw, if I was to add a Sony, it would be at least an A7R iii and I wouldn't touch an A7R ii with a 10 foot pole.