Plex does HW as long as it’s not setup as a service in Windows I believe
You could mix and match stuff…
i5-8400 can handle 3-6@1080p (2k bench per 1080p stream and it clocks at ~11731) and offload some to the iGPU if things bog down or you decide to toss in a 4k stream.
CPU will give better video quality but HW is nice if you want to budget a bit
Note that Nvidia cards are locked at 2 streams unless you go quadro
Someone here did post they had a Ryzen 2400G (9k benchmark) working using HW in windows so that might work and cost a significant amount less.