Your only video card options are the one from your old computer or integrated chipset graphics, either of which will handle productivity plus some light gaming, but probably no more than that. You definitely need a video card but can’t realistically buy one until 2022, so those are your only two choices.
Honestly, and call me crazy, I think I might recommend building out your system with a temporary cpu instead of a temporary video card. Specifically this one:
AMD Ryzen 5 3400G 4-core (Best Buy link)
The “Vega 11” onboard graphics it comes with is leaps and bounds better than intel’s equivalent. The cpu itself kind of stinks, being slightly slower than my lower end Intel i5-10400, but again, way better graphics. (Here’s a UserBenchmark comparison of the two.)
Here’s the kicker: That cpu on Best Buy is only $150, whereas it’s $240 on Newegg and $275 on Amazon. I don’t know why it’s so cheap right now on Best Buy but that’s a great price for a “temporary video card.”
If you do go this route, verify that the Ryzen 5 3400G uses the same motherboard socket as whatever ryzen chip you want to upgrade to once the video card comes in. I have no idea if different ryzen chips fit into different sockets, or even what “generation” a “5 3400G” is. I don’t know anything about AMD stuff; I’m an Intel guy.
For Intel, reviews of the just-released 11th generation chips are generally terrible, in many or most cases being outperformed by the same model 10th generation chips they’re supposed to be replacing. The 11-10600K (unlocked) is an okay value chip, but other than that, stick to the 10th generation. Should be cheaper anyway. As a general rule, Ryzen is way ahead of Intel at all levels.