question Single letter/number domains availability

[Nothing]

Single letter/number availability to handreg purchase

 

[Ollie3000]

If you're asking whether you can handreg single letters & numbers then the answer is no they went a long time ago.

There may be some ngtlds where single letter & numbers are still available but they're reserved with premium pricing, so yes you may be able to reg but not cheap and this is still unlikely.