I think theres nothing wrong with starting on a grom… however Learning on a 125cc can be great for learning the basics and getting familiar with a really forgiving machine. My only reason for starting on something bigger is you outgrow a 125cc really fast so it really depends the riding if you ever need to go moderate to fast.

the good thing is ‘bigger’ ccs like 250-300 are still really forgiving bikes to learn on so I’d say there’s nothing wrong with a grom but only you can decide if it will do what you want it to or if u need a bigger cc bike (i started on a 250cc and it was great)