Transportation from Florence to Trasquera

Hi! My gf and I are going to Italy in September. We are spending the first 4 days in Florence and then we got an AirBnB up in Trasquera for the remainder of the time. I am having the hardest time trying to figure out how to get from Florence up to Trasquera. I know I can take a train, with two changes, from Florence up to Domodossola. However, getting from Domodossola to Trasquera seems to be the difficult part. I think the train is run by the Swiss up there, but can’t confirm and haven’t been able to find any info on it. Has anyone been up that way and know how to get around? We’re also considering renting a car when we’re up there but not really sure where to rent from or if it’s all that necessary. Any advice would be greatly appreciated!