You came in with a misinformed wall of text touting every high-powered card you'd ever heard of.
Thank you for taking time to point out my errors. Again I'm not a Vegas user. I use After Effects & Premiere rendering at 2560x1440, they benefits from large VRAM, quanitiy of CUDA cores and on-die caches, with a $200 amount of budget, the 2nd hand Tesla P40 & RTX 3060 12GB falls into the OP's requirement by their computing power & larger VRAM size initially.
Vegas is notorious for not benefiting from hot graphics card hardware. Which you'd know if you had any experience with it.
I did some research after replying to you, now I understood that your recommendation of 2060S is solely for the NVENC module & VRAM bandwidth rather than it's computing capability. You may be right on OP's target workload is light rather than heavy.
a Quadro, when the guy asked about $200 cards?
The reason that I recommended Quadro cards was because they were proven to be more stable than GeForce for rendering. However since Vegas invested more on OpenCL, an AMD card is more likely to be helpful.
He's looking for hardware encoding and some light effects, by the sounds of it.
I still don't agree with you on this phrase, as we do not know what OP is looking for at first place, to me he/she is looking for a rendering boost, which natually requries a powerful card, no matter what budget the OP has.
BTW, if you pay attention, you'll see that I didn't actually recommended any cards at first place. I firstly recommended to get a faster CPU at my 1st reply.