I really want to buy that, but why is there no Linux port?
It's already on Android, so porting it to Desktop Linux shouldn't be a problem.
As mentioned to you on our Discord, doing a proper Linux version would force us to halt all other development (meaning, working on our current project) for an indefinite period of time (anywhere from a week to a month). Unfortunately, our team is not big enough to be able to keep working on new stuff while also delegating someone to research Linux support.
Since we are not using the platform ourselves and thus cannot really guarantee doing a proper native Linux port, we've opted not to make one. We've got accounts of people saying that they've had no issues emulating the game on Linux via Proton, but for obvious reasons we cannot give any guarantees of that working across all distributions and driver configurations.