I was just on a such a project. Output was via custom binary format send through BT. Commands where generated through a wpf app. The code did not follow separation of concerns or MVVM at all. Just trying to disentangle Bluetooth from wpf was a major task with several unforeseen side effects (e..g newer code was just faster, which crashed the receiving BT device...).

Ultimately the contact for me was axed because the root cause (bad leadership) just did not understand that bad code needs fixing before velocity can go up again.