

Port forwarding lets you connect with other hosts peer-to-peer which a VPN would otherwise block if both sides are behind one. For torrents you’d get more peers (which doesn’t matter if you’re just downloading the latest and most popular stuff) and be able to seed more effectively.
Some bank apps work on LineageOS, some don’t. Mine does, and I’ve only used it twice in ten years, but I’d sooner switch banks than run Google’s android.