I might, for once, slightly disagree with Jaffa
I agree that softboards are primarily surfschool and not for significant progression, but their main benefits are ease of catching waves and 'safety', as they are soft.
A 7yr old, if anything like mine:
- wont have the stregth to control a board when hitting white water etc (eg 'duck diving'), so it will be flying around a bit
- probably will spend a lot of their time near or
inside the flags, where softboards are allowed (usually) but hard boards are not
- will not create too much damage when they smack their parents in the face with board when the parents are helping out - if its a softboard
- will struggle to catch waves (unless an excellent swimmer) by themselves, so the more assistance the better
I have seen little kids very capable on grommet boards, but most of them are still being assisted by their parents and the parents always look like full on full time surfer types; the casual non surfing parent or casual just learning to surf kid is a fair way from this.
I reckon a good quality softboard around 6 to 6.5ft is the way to go, maybe 7ft if he is a bit larger than average. This will keep him going for 2-3 years and by then he will be ready for a proper board.
Softboards do vary in quality; some are just heaps of foam (like a bodyboard made larger) and these flex and are terrible. Others are much better designed and are not a huge distance from a standard hardboard, but of course are more expensive.
Either way, I would also try and find some soft fins, or rubber edged fins, just as extra protection.
A good quality softboard are the el nino boards (eg the flow or the fluid)
https://www.elninosurf.com.au/ but I dont know if they are available where you are. The prices may also be more than you are thinking about
Others I have seen recommended, but cant vouch for personally, include
Of course, as jaffa said, maybe discuss what he wants before springing something.
good luck - great uncle!