I think the point that @vbier was making is not that it can’t be done but that he is still learning android development and what has already been done to date is platform specific therefore you’d be back to starting again.
Personally I’m not a mobile platform developer expert either, I just had a play for a few days with React/NodeJS and compiled to test a one or two page screen with random content. It wasn’t that challenging to do but it was a useless app and I certainly didn’t feel comfortably in control of what I was doing so back to the other point @vbier was making is it would still be a new language to him hence another learning curve.
I suspect if a cross platform version was to have any hope of getting started and then catching up to where this app is already at any time soon we need an experienced mobile developer. The cross platform tools are pretty impressive but they are also an abstraction layer and the app has some quite reasonable demands on the hardware around the motion detection and stuff so you need to be careful around the platform selection. You want ease of development but there’s a possibility you may also need to get under the hood with platform specific variations. An experienced mobile developer could probably advise whats best from their knowledge base but the rest of us would have to do that research before even starting.
Then we need to talk about who’s going to do release management and signing of any App you want to run on an iDevice through the App Store. The Android version can get away without it if apk installs are enable but I don’t think you can do that in Apples world, it has it’s advantages for security reasons but just adds more work to a project like this.
I suspect if someone could deliver a new project tomorrow or next week that was cross platform and contained the existing features already active in this one you might find the likes of @vbier may consider switching over to join in. But at the moment it looks like he’s put in a fair amount of effort to get this off the ground and he’s starting to see rewarding results and he doesn’t want to take a three to four month diversion to research, learn and rewrite.
Everything is possible but needs some additional resource to get hands on and start it or wait until…