GMKtec K12 Gaming Mini PC Oculink AMD Ryzen 7 H 255 (Upgraded 8745HS) 32GB DDR5 RAM 512GB SSD, Desktop Computer Radeon 780M Graphics, 3X M.2 2280 Storage Expansion, Dual NIC 2.5G, HDMI 2.1, USB4

OP I'm doing the exact same thing, although I doubt we will find a <518$ for those specs. I was THINKING about like the GMKtech unit: https://a.co/d/08dsImkb But it's like 170$ more, with the faster 5600mhz RAM, and same 1 year warranty..

So at the $700 price point you want something with AMD 780M integrated graphics, that's pretty much the most important thing for determining performance in games and what to look for in the specs. You also want 24 or 32 GB of ram. Beelink and GMTek are reputable brands. Something like this: https://www.amazon.com/GMKtec_gaming_mini_pc_ryzen_h_255/dp/B0FK2BLV7J/ (I can't vouch for the specific listing but the specs are good)