This is a small shim that can be built into a flatpak app to get a working version of xdg-open and xdg-email. Made for electron apps which need both utilities, but should be suitable for any flatpak app needing those tools.
Other xdg-utils scripts are of dubious value inside the sandbox, and were not included.
This shim requires the gdbus utility, which is included in the freedesktop runtime.