My all road bike was built with 650b wheels since I didn't want skinny tires. The issue is that with this wheel size the bottom bracket is about 15…30 mm lower compared to 700c so you'll have to be careful with crank length due to the increased risk of pedal strike. Most of these bikes have a bottom bracket drop of 70 mm or more, while a frame designed for 650b specifically will have 54…60 mm. I don't know why the industry doesn't build frames with 65 mm BB drop since it would be in between, but I'm inclined to believe they prioritize 700c with 40…50 mm tires. But then one wouldn't be able to use anorher wheelset with skinny 25 mm tires for road, so you'll probably need a road bike. While designing for single wheel size only, the industry also ignores the needs of shorter people and most women.

My cross bike will take up to a 38mm 700c tire but I can size up to 45mm 650b with no changes! Small miracle of dropping rim brakes.