Yea, I'm sure they have some pretty strict regulations with that kind of stuff. Turbo Native has come very far with integrating with hardware so you can use all of the hardware components that you need to, but you also would have to create the iOS app and Kotlin app. But it's still a lot less work than a React Native app or a standalone app. Hybrid is the current flavor of the "rails way". However, if that isn't an option to go hybrid due to requirements or policies, then React Native, Xamrin or similar could still be an easier route than a standalone Android and standalone iOS app.

I typically prefer the turbo_stream responses in the controller action as well. But, I think there's a use case in each scenario.

You can use the one postgresql instance and have multiple databases on that instance. You do not need to create separate instances (one for each database). If you have specific requirements because maybe a queue database or cache database has different infrastructure requirements, then you should be able to set up additional servers and use the accessories for each of those servers to host their own container of postgresql. But if we're talking a more simple setup (everything on one box/vm) then you would need just the one postgresql instance (even with multiple databases).

I don't have a Synology NAS and it's weird that you can manually run it but it doesn't work with Kamal. Personally, I don't think a NAS is a good place to put containers/VMs. Mainly because when you have file systems like ZFS, I'd want the NAS to be able to allocate as much RAM as it can to ARC. The machine that I used on this episode was an Intel Ultra 7 155H ASUS NUC. https://www.asus.com/us/displays-desktops/nucs/nuc-mini-pcs/asus-nuc-14-pro/

Additional comment about the video. I'm not sure if I conveyed it well, but one of the awesome things about using Cloudflare Tunnels is that you don't have to make any changes to your network, including opening up any ports on your firewall/router. This means that you could run this on your home network or even a school network (assuming that they're not blocking certain kinds of traffic). But always check with your ISP and/or provider to see if you're within their terms of use.

Another cool thing about this approach is that if you do have a Dynamic IP Address then everything will continue to work if your ISP gives you a different IP. You won't have to go into your DNS provider to update IP Addresses. This is because the Cloudflare Tunnel initiates an outgoing request to Cloudflare's servers and keeps a connection open.