First, network overlays are not easier to setup than VPNs. Installing and configuring a network overlay client on every device is much more work than setting up a single VPN tunnel for every network you want to access. Overlay networks are just easier to plan because there is no planning. But they're not easier to implement.
Second, and far more important, meshing all your devices into a single flat network is dangerous. There is a reason why networks are designed with isolation strategies. Introducing an overlay into your networks breaks down these barriers for you, but also for an attacker.
The only overlay network that has built in firewall capabilities is Nebula. When I started configuring its firewall rules I found myself just recreating my existing segmented networks, but in a much more obtuse way. Instead of configuring a central firewall, I was configuring firewall rules on each device.
After all my research, I'm still running the same segmented network I was running before my overlay experiments. But I would like to give some praise to both Nebula and Yggdrasil. IMHO, these are the two most existing projects coming out of this space right now.
What prevents you from meshing the individual services on a per-need basis? The fact that they're overlays makes them even more convenient for such isolation.
> The only overlay network that has built in firewall capabilities is Nebula.
Are those built in firewall capabilities really missing from the other networks?
As far as I know, ZeroTier is more of a SDN that an simple overlay (That's what made me interested in ZeroTier in the first place). If conventional "L4 transport-layer" firewall/routing capabilites are enough for real networks, then ZeroTier SDN capabilities are probably enough for it's virtual networks. Granted, it doesn't have some nice built-in high-level generic "L7 application-level" firewall capabilities, but I don't trust those in the first place.
you do need to look for an ISP that gives you a static ip which isnt even possible where i live