I have tried many VC and Leica lenses (and other mounts too) adapted to all sorts of X camera over my ownership history. The constant reminder for me is:
native lenses only!!
I have 50 and 35 lux and I just dont like them on the xpro2. I would never suggest someone buy Leica glass to use just for adapting purposes, if you already have them then experiment, but there are plenty of other adaptable mounts that will give similar results on the Xpro2 if you want to dabble. I have also found that EVF and peaking with manual lenses is no longer something I enjoy (but that is the rangefinder fanboy speaking).
The only mirrorless that does leica lenses well is the.... Leica SL....I bought one and sold it.
If you can find lenses for under say $150 to play with or to get a vintage or classic look, that's fine. For the money, the X prime set of 23, 25, 50 cannot be beat with any adapted lens.
I would experiment with M42 more than anything M mount. Buy 1-3 cheap Helios 44 or takumar SMC 50mm 1.4 and have fun!
Just from the examples the 50 lux will never look 4x better than the 56mm (but it's 4x the cost!).