I find myself a bit confused, as I'm not an expert in this field. I'm looking for advice on what to use: ZeroTier, HeadScale, or Netmaker. My goal is to place my services behind a VPN for added security. I'm wondering which of these options is better and more secure. Is it worth comparing Netmaker to HeadScale and ZeroTier, or are they best suited for different purposes? If I opt for ZeroTier, is self-hosting a better choice, or should I go with their free plan?