While the official RollerCoaster Tycoon games are available on just about any platform you want, its the open-source version of the game that fans have been busy keeping alive. Titled OpenRCT2, one clever modder has brought the whole thing over to the Switch, complete with some touchscreen support.
You can find the Switch port on Github here, although you'll still need an original copy of Rollercoaster Tycoon 2, like the PC version of game. It's developed by rsn8887, a homebrew dev who ported OpenTTD and Caesar 3 to the Switch, along with making various improvements to Retroarch for the Switch and Vita.
Because it's a homebrew project, OpenRCT2 won't work with a standard Switch console. You'll have to go through the homebrew process. If you're prepared to take that risk, the install process for OpenRCT2 is fairly easy.
The homebrew community has spent a lot of time over the last year getting hardware acceleration and OpenGL support. Having the latter means Switch ports can take advantage of the Switch's GPU, instead of relying on infinitely slower software acceleration. OpenRCT2 is one of those games, and other uses include a proper release of the Retroarch emulator and a port of the classic '90s shooter Blood. There's even footage of someone playing Morrowind, or at least the open source version OpenMW.
Seems like the Switch isn't doing too bad at being that handheld PC console everyone wanted.