He also says somewhere in the comments that apple simply wouldn’t allow this app on the app store. But there’s also the option of sideloading, I think that’s free no?

He says in the video on yt that you can fork it and modify it however you want for personal use no problem. You just can’t make money distributing it I think.

Is the time of loading and downloading the files from the flash drives of the pigeon included?

Never open ports to the internet unless you want everybody to see it. Always use VPN to access your selfhosted stuff. If you’ve got a lot of VPN connections to set up, try generating a QR code for the connection. Makes it a bit faster to setup the client.