I have a flight upcoming booked with TAP, but utilising a leg with GOL. Specifically Foz Du Iguazu to Sao Paulo. Does anyone have any experience of such a booking to share, or watchouts to look out for?

The booking is TAP Business Class. I'm going to assume there is no Business Class on GOL. Do they have a permium check-in, or will it be a single class check-in and flight. Can I expect luggage to check through or will I need to collect in Sao Paulo? Seat choice, I don't seem to be able to select through the TAP App. Should I try to GOL website? Will check-in be via the TAP site or GOL site? Anything else to consider.