>>3403977They could make Q FF mirrorless I'm sure, but why would they?
If they join L-mount they can sell more bodies if they fill the niche of ruggedized/weatherized FF mirrorless, while developing killer L glass that will sell to the entire market of Leica/Panasonic/Sigma/Pentax (and maybe Olympus if they join too) body owners. There's literally no downside.