they can tell im watching video, but the connection is over https, they can’t tell im watching episode one of star trek or whatever. unless they’re doing a mtm on all their customers to intercept SSL certs for the express purpose of traffic snooping.
ive been doing this for years on an ISP that has previously sent us a nasty note about piracy when someone did a torrent, so I think i’m probably ok man.
if you want to go the SBC route there’s other options aside from Pis you might want to check out. Cheaper and more suitable systems that are easier to get ahold of. If you’re looking to get into it I’d look at LibreElec and Kodi with a Seren plugin setup that pulls from a Debrid service like RealDebrid. debrid removes the need for a vpn and is usually cheaper and faster.