A max of 50Mbps sounds like crap hardware or other problems in the setup for those people you spoke to. For example, testing over WiFi, testing from a phone/mobile device, using 100Mbps powerline adapters... The speed test I posted in post #3 above (902 Mbps) was on NordVPN using NordLynx (their WireGuard implementation).
You're in a bit of a circular argument at the moment. You won't upgrade your powerline adapters until you know you'll get better speeds, but you'll never get better speeds until you update yoru adapters! As I hope I've demonstrated in this thread, with the appropriately powerful hardware and a decent connection (i.e. a decent desktop PC with a strong CPU, cat5e cable or above and WireGuard) you'll easily get many multiples of the speeds you're currently capped at.
If privacy and security is important to you, though, any of the big no-log providers will likely be OK. Nord has its problems and limitations as I said (nothing to do with speed), but with the current cashback offers provided you go in eyes-open worrying about logs isn't one of them. As with anything, it's a balancing act.
WireGuard is a protocol, a way of connecting two networks together. In other words it's a type of VPN. Other types/protocols are OpenVPN, IPSEC/IKEv2, L2TP etc. If you wish to travel from London to Manchester, you might take a car, a bus or a train. They do the same thing but they're different. Similarly, the various VPN protocols do a similar thing, just in a different way. WireGuard in particular is very fast, light and secure and will generally provide the fastest speeds available. Some VPN apps have WireGuard built in at the moment (eg Mullvad, AzireVPN, OVPN, NordVPN, PIA). In many cases, you can download the official generic WireGuard app direct from wireguard.com and import the config files your VPN provider gave you. Some providers like NordVPN and PIA won't give you the actual files, they rely on their apps to connect. Others, like (again) Mullvad, OVPN and Azire, will let you generate and manage your own configs and you can connect to them how you wish (their app, WireGuard's own app, Linux kernel CLI tools etc).