Getting another number helps a lot in my opinion. If you’re getting another sim in the same phone, I suppose it would be possible for whatever cell carrier is providing the service to be able to link your two sim cards to your identity. However, for other companies, I don’t know of a way they could gather that your second sim phone number is linked to your first one. For instance, if you created two Discord accounts with your two phone numbers, you could theoretically be two completely different users that won’t be linked together. I would personally go for a second number.

Have never had a problem using a VPN with programming.dev

I’m aware of a network that blocks Mullvad as well, but found a way around it. It went through just fine if I was using a custom DNS server. I used NextDNS for this, but I imagine it would work with Cloudflare or something as well (but I highly recommend NextDNS anyways). Hope this helps!

I’m unsure as to what info is sent other than your IP with Newpipe, but you’re correct that it will get a VPN address instead. Commenting to suggest a fork of Newpipe known as Tubular. Has SponsorBlock and Return YouTube Dislike functionality!

Mullvad is better imo, unless you need port forwarding. I’m currently using Proton since I pay for Unlimited for that encrypted drive space, and using their VPN saves me money since I just think of the payment as just for Proton Drive. This is a change I made just a few days ago though, for about a year I’ve paid for both Proton Unlimited and Mullvad, and I legitimately prefer Mullvad over Proton, it just made sense for me to switch money wise. Can’t really go wrong between the two imo.

If buying new, I believe you can ask to have the modem removed from the vehicle, which wouldn’t allow your car to access the internet. Haven’t had the opportunity to try this myself yet, but very much plan on it for whatever vehicle I purchase new in the future.