QuickSync is usually plenty to transcode. You will get more performance with a dedicated GPU, but the power consumption will increase massively.
Nvidia also has a limit how many streams can be transcoded at the same time. There are driver hacks to circumvent that.
You can easily do that manually. The “mesh” part is either awareness of other routers for using 802.11k or awareness with wireless backhaul.
If you don’t need 802.11k or easy wireless backhaul, you don’t need mesh routers.