Though the topic is stale, maybe a new approach might be possible for the Launchbox team. Identifying the needs vs the wants for Launchbox on Linux by ignoring feature parity with the current client.
There isn't any other front end with a competent meta data ecosystem on any platform. This is truly what makes Launchbox unique and special compared to it's competition, not to ignore all it's amazing features it provides. The second best front end is Emulation Station which is open source, but the meta data is not free and Skraper horribly slow/limited considering they want payment.
Maybe forking Emulation Station (Launch Station?) and using the license key to access the Launchbox db could be a realistic solution that can be brought forward? Even if Emulation Station would require payout for using their code, just mark up the Linux license to cover the difference?
Feature parity can be ignored as long as the meta data system works properly, it's honestly why everyone is here.
Considering the popularity of the Steam Deck and Linux moving forward, a fork of trusted open source software might be the better solution. Most issues can be addressed with Emulation Station as the main product here is the meta data system that needs to be implemented.