Jacket is like a torrent tracker consolidator. Is your goal to be able to do a jacket powered torrent search through qbittorrent?
IMO these are complimentary tools and you don't need to implement jackett as a plugin into qbittorrent. That feels overly complicated.
I would spin up jackett in a docker container and then set it up to do what you need with qbittorrent as your torrent downloader.
I agree. Run everything you want and then when you see performance degradation then you'll know the limits of your hardware based on your workloads.
You already have the NUC so why not push it's limits? The alternative is to try and guestimate your workload needs and buy matching hardware... which is very difficult.