No, because Fortnite doesn't have a LAN mode. Minecraft wouldn't work either because if they want to play with their friends online, all their friends would need modded switches as well, and they wouldn't be able to play on big multiplayer servers or anything, just with friends on modded consoles by themselves. Splatoon 2 would work without their friends needed modded consoles, but the other kids would need to know how to set up LAN play and all that, and most kids won't know how to do this. Plus again, they would be mostly playing with their friends by themselves because LAN play doesn't have many people on at one time. It also doesn't have ranks and unlockables and stuff like that, which is the fun part of playing online for most.
Plus, newer consoles need mod chips in order to install SX OS. The chip will run you $60, plus another $60 to install it unless you have good micro soldering skills and equipment. It's not something the average person can do. Fortnite is free, Minecraft is $30 and Splatoon 2 is $60, so it would be cheaper to just buy the games.
However, if you wanted them to have free games for single player use, you could mod the systems, buy the games, and they could use a clean Sysnand to play the bought game online, and use an Emunand to use CFW on and play single player games not needing online on there.
