it looks like the
M7100 series has gone Micro Spline, but not the previous
M7000. I'd be surprised if there's a modification possible as Shimano tends to design hubs to be set up only one way, unlike many other hub manufacturers that allow you to swap axles sizes and freehubs. If getting a 12-speed cassette with a 10t driver seems worth it to you, you
probably need a new hub.