looking into a mobility service dog

i’m in oklahoma and I was diagnosed with multiple sclerosis in december of 2023. my mobility is getting progressively worse and i was looking into a service animal! i’ve seen a lot of different information online about how to get one so i wanted to reach out and ask how everyone else did it! i wanna go the self training route but due to circumstances i will have to do it with a trainer. i haven’t picked out a breed but i know that i’m going to be buying from a breeder but i’m unsure what breed would be best, i’m looking into a newfoundland or some sorta large sturdy breed. is there anyone here in oklahoma who may be able to help me on how to go about finding a good trainer that has payment plans or something along those lines? i really just need some good information on how to get started and what to expect, etc. any help is GREATLY appreciated!! 🧡