I just saved myself $80 by repurposing my old G26's Mitch Rosen EXP-UPL holster, and from what I can tell, it fits my Shield perfectly. The extra leather needed for the thicker G26 seems to perfectly accommodate the extra material needed for the greater difference between the bottom of the trigger guard and the top of the slide & sights of my Shield. I can shake it fairly briskly and it will hold. I wouldn't do a flip like a dancing FBI agent, but I wouldn't do that anyway.
I wouldn't be surprised if Mitch Rosen uses the same or near same template for both the Shield and G26.
I can also use my SIG P229's Old Trail Leather pancake holster for my M&P9 M2.0 Subcompact. This one is not as perfect (the G26/Shield seem like a perfect fit), but this particular holster certainly close enough in my opinion. This one saved me about $60.
It pays to check your box of old holsters, that's for sure. I wouldn't necessarily use the P229 holster as my main M&P Subcompact holster, but I definitely would use the G26 for my Shield.