Hi Alexandria,
I don't have too much to add here, but I just wanted to say, my husband and I are currently going through the exact same process!
He came over to the US 5 years ago and we are currently looking at applying for a spouse visa for me so we can both relocate to the UK. He also meets the financial requirements with his US employment, so he is just actively applying for jobs in the UK (which is tricky, given the current pandemic!). Once he gets an offer letter, we can go ahead and apply, but since it could take up to three months, there's the possibility he would have to go over first without me, which is a bit of a bummer
As far as your online application question, it's my understanding that all supporting documents should be uploaded digitally, and it is only your passport that is sent off (AFTER your biometrics appointment).
Anyway, I just wanted to say that I completely understand what your going through, and let me know if you ever want to chat about the crazy process!