My son has said that he would love his own piano in his bedroom

I
don't think it's just a phase, and I know how he is with his music - although he's quite happy doing his practice and playing his pieces downstairs for all to hear, there are other things he wants to do in private. With the guitar, he'll play it anywhere, but his 'private' stuff - composing and improvising and experimenting - he does in his room. At the moment he does very little of this on the piano, though he used to do more. I haven't said yes or no, or even that I'd think about it. I'm certainly not rushing into anything and I'm waiting to see whether he mentions it again, as it came out of the blue last night. But it wasn't just a whiney 'I want' - he has obviously been thinking about it a lot.
There's no room for a piano in there (I can just imagine trying to get the upright up the stairs - even if I was prepared to let it out of the living room, which I'm not) and I don't think his bedroom floor would take the weight anyway. So I was thinking of a keyboard, but I have absolutely no knowledge or experience of these.
So as a bit of background research while I see what develops, does anyone have any advice? Would a keyboard in his room be a good thing? Does a keyboard sound right for the sort of thing he wants to do? If so, any recommendations? Any pointers would be welcome, thank you