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.

Here’s a video covering basically all of NextDNS’ settings! https://www.youtube.com/watch?v=WUG57ynLb8I

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!