That’s pretty common actually. It’s called IWB CC (Inside Waist Band Concealed Carry). There’s also AIWB (Appendix Inside Waistband), sometimes just called Appendix carry. The big issue is that it’s not inside a holster. The holster gaurds the trigger so that an ND is more difficult. Holsters also have retention so you’re less likely to have a gun drop, where the gun falls off your person unexpectedly.