Nice job so far. A couple points.
1. Memory express does price matching if you buy from them
2. That power supply will absolutely work, but I always recommend not cheang out on it since it keeps everything going. For $20 more, this is the cheapest one I see right now that I would grab:
3. motherboard is a fine choice. B550 based motherboards have a few more features (newer version), and I believe you mentioned wanting wifi. This one is the newer b550 and has wifi built in (for your consideration, not a must):
4. Graphics card - this is almost always the limiting factor in a decent gaming computer. You can literally spend your entire budget on just a graphics card. A 1660 super should get decent fps at good settings at 1080p without issue. Obviously more is always better, but at a cost. You may get lucky on a used rtx2060 /2060 super/or 2070 with people trying to upgrade. Or you can take the extra cost new.