...because that's EMULATION, not a PORT, know the difference.
Neither did the XB1, yet you can play it on that.
Because GTA IV came out in 2008 and the Nintendo Switch didn't exist then. As for now, no ports of GTA IV have even been hinted at so you can't really cry about it not being on the Switch when it's on nothing.
Why Rockstar not release a version for Nintendo Switch? It would be great if you can play GTA4 on Switch whenever you are outside or at home.
Please do establish the difference between the two.