Considering you are using Proton, you care about digital privacy. If you are not trusting Proton, you should not trust Tailscale as well, in my opinion. Tailscale’s backend is closed-source, you get no control, and nothing is stopping them from selling you data either. If you go for Headscale, you may be in a slightly better position. But websites and big companies like Google can still make detailed profile of you, as you will be connecting to everything using a single IP, that is, the IP of your VPS. But again, nobody is stopping your VPS provider from selling your data either.
Another question is that why are you paying $19 for that? They have $10-12 plans that come with 500 GB storage, emails with 3 custom domains and high-speed VPN.
Also, if you do not trust Proton, you can consider Mullvad or IVPN. They are just $5/m, and you can pay via Monero, but they do not have as many servers as Proton does.
Another question that pops in my mind is, why do you need a VPN? Do you need to connect to your services privately, or do you just need to change your IP for (relatively) better privacy? Again, paying someone with multiple VPN options is better than setting up a single VPN by yourself, in my opinion.