Has anyone had success mixing and matching cassette sprockets for custom ratios? I have a 9 speed rear cassette that I am looking to replace some or all of. I would love to have a 9 speed cassette with a 10 tooth or even 9 tooth top gear, but the combination doesn't seem to be available with existing cassettes, so I am contemplating a mix and match affair.

I know each sprocket is indexed and has particular profiles to smooth the down and upshifts depending where around the cassette the shift happens, so this might make the idea a bit crap.

Alternately can someone point to an existing 9 speed cassette that is 10-28 or 9-28?
As far as I’m aware there are no 10 teeth sprockets for normal Shimano hyperglide freehub bodies because the freehub diameter is just too large. That’s why SRAM created the XD Driver standard and Shimano created the Micro Spline standard. 

Can’t you install a larger chainring and use a 11–30 cassette?