Just look for either semi-auto rifle or pump. I have 30-06 Rem. 7600 that is a pump so I can shoot either hand and it doesn’t make a difference. I do have some right hand bolt action rifles and shoot them either way its just takes some getting use to. Shooting the bolt left handed works well if you have bi-pod then your hand never has to leave the trigger, but if your a true rifleman none of that should matter since “its a one shot one kill.”
In general, I think it’s better to make a choice and then have the young hunter stick with it.
Keep in mind that it’s not just the action and port that’s on the opposite side. On a true left-handed rifle or shotgun, the stock will be cast off to the left as well. Now I’m aware that not every rifle or shotgun in today’s standardized and mass produced world will have a cast, but if it does…
Fortunately these days we are spoiled for choice when it comes to rifles that are a)both affordable and accurate and b)come in left-handed versions. Even finding a rifle–any rifle–in a left handed format used to be a challenge and many, like you, just made due with the rifles they had available.
Now with the number of really good rifles you can get for under $500, there’s a lot more options for getting even the young shooter a decent rifle that fits them both in terms of overall fit and for the correct hand for them.
Grouse