$900 won't get you much of a new bike currently. Everyone's been buying up entry-level bikes, plus the supply chain has been disrupted since last year.
In normal times the best advice would be to go test ride bikes at local bike shops, but many are out of stock of the cheaper options.
It's a big risk to buy a bike without having any idea how it fits and feels to you personally. Try your luck with local inventory or wait out the pandemic if you're in no hurry. Take a flyer on a bike from an online seller only if you're desperate for a road bike.