I’ve got both Node 2i and Lumin U1 Mini. These are (or were) both feeding a Sonic Frontiers SFD-2 MK3. Despite its age this is a truly a super-DAC even now, extremely hard to improve on. The very few who have heard will agree (I say this to try and short circuit the usual "old digital can’t compete" arguements from posters who haven’t ever heard it). Anyway, that feeds an extremely revealing, high resolution system. I have no use for MDA so that isn't at play here.
My conclusion: Sonically, the Lumin clearly beats the Node 2i. But the Lumin UI is just a bad joke, so much so that I’ll sometimes use the 2i for that reason. I’m on Android, maybe Apple works better. BlueOS seems to work great on all devices.