Out of curiosity, why did you opt for an X570 board to then populate with a 2700X? B450 or X470 would've been more than adequate, and likely a fair bit cheaper?
Borrow/buy... once you have the CPU, I'd seriously consider buying a basic display 'out' GPU locally if available, $10-$20 variety, just to test. While if all works well, you're "out" said $20, if something is a problem, you may well "save" >$50 depending on the component just by being able to return it in good time.
If something is DOA and you miss the retailers return window, you can still proceed with an RMA from any manufacturer, so you're not out-out the money.... but you would have to ship the part to X manufacturer and wait from a reply/return, so you'd be out time + one-way shipping costs.