The hub is probably made for 14g spokes, standard size.
I have heard of some people drilling out the holes in the hub, but that isn't advised because it weakens the hub.
The hub would have to be 36 holes to match the rim also.
I'm sure it's most likely 36 holes. But yeah the hub spoke holes size that's where I run into a stop on the idea.
On the other hand I could just buy the entire wheel but it's an s7 wheel so can't get that fatty tire on it.
A regular 26" rim is 559 diameter, S7 is 571 mm. Difference of 12 mm, but only 6 mm radius. If the spoke threads past the end of the nipple, grind it off. You then use the same spokes. That's what the guys at the bike shop do where I've taken some oddball wheels I've laced up. Take the hand held grinder to the threads sticking up past the nipple.
If the wheel now is laced 3 cross, you may also be able to lace it 4 cross to make up the difference and use the same spokes. To determine the exact spoke length will depend on the size of the hub and the size of the rim. I use a calculator to get the size. If my spokes are 3 or 4 mm different, it still works out most times.