Does anyone know if there is a software for Mac that lets you stream on 2ds xl.

I believe you need a handheld specific capture card. They're custom made and cost a lot.

wiiuvc has ds emulation yeah? though I don't know about 3ds

Yeah, DS/3DS capture cards will run you around $250 minimum for the capture card installation if it's from a respectable source.

If you go that route though, whoever installs the capture board should offer the driver downloads (including Mac versions). If you don't see it listed, double check with the seller before purchasing.