I am giving my Daughter my old PC. I ordered this PC from Amazon (remember I am doing it CHEAP)
https://www.amazon.com/gp/product/B0DJXW682F/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Not sure if you knew this already, but there are ThinClients which pop up on the used market now and then with pretty much the same specs and much smaller footprint. The HP T740 ThinClient is a bit thicker than most, but has 2 SODIMM slots, an NVME slot, M.2 SSD slot and the one for smaller cards (A-Key?) for wireless, which can be used for other purposes if desired. What sets it apart from other thin clients is that it also has a single full-size PCIE slot for half-height cards. It's virtually identical in ports as well. The only mildly annoying thing about them (and the one you bought too) is the 4 DP ports, but no HDMI ports. The T740 also lacks normal SATA drive connections, which can be remedied thanks to the PCIE slot, if you really need them, but the card would need to supply power to the drive as well (not sure something like that exists.)
I managed to snag a quantity of HP T740's for general/development use and they came out to about
$40 each (!) with 8gb of PC4 3200 SODIMMs in Dual Channel, Wifi, Bluetooth, 64GB EMMC drive and a power brick. Even with those specs, they make great little special purpose Linux devices (or even Windows 11 if you are a masochist). They aren't always easy to find at that price and with those specs, but they are very upgradeable and at less than half the cost of a decent Pi (or even at the full cost), they are a no brainer.
RE: Linux
If you are heading in that direction, pick up a cheap system now (or dedicate an old unused system) and start playing. The options for distros have become amazing lately, and Valve is even getting ready to put out a Steam version specifically geared toward gaming. It won't be long after that we start seeing forks of that distro (if even necessary) which combines excellent PC gaming with other general use capabilities. Once this happens, MS is is going to become irrelevant to a large chunk of the gaming market they currently have a stranglehold on.
No time like the present. By time Win10 dies off, you'll already be well on the way to make the switch. If emulation is the main thing you play around with, I'm not sure it would take you more than a week to not care about Windows anymore, unless there is some program that you absolutely must have and it can't be run under compatibility tools like Wine.
RE: Graphics card
What BlueGhost said. You won't really be gaining much with that card and it doesn't even provide you with the more common HDMI ports. If you really want to step up the graphics, you'll probably need to spend more. But if you do, keep in mind that Linux is geared toward AMD graphics. There are closed-source Nvidia drivers, as well as newer open-source ones which are getting better, but AMD stuff is usually more compatible out-of-the-box and less likely to have weird issues.