they already supported mobile hardware tho?
Some of it. YEBIS lighting/DoF technology is everywhere, even a few Vita games (I don't think the Bravely games used it though?) It's characterized by that insane glow and pillowy soft-focus that's seen in 3D.Game Heroes and World of Final Fantasy. YEBIS is integrated into other game engines as well as Silicon Studio's own engines, so you see it used in Square's Agni's Philosophy, Yakuza games and stuff like that. (It can look amazing, but it's not always dialed up to 11 BTW, and I'm sure you've actually seen YEBIS used in a number of games that you paid no mind to, like the Milestone racing games, Neptunias, DB Xenoverse, etc.)
There's a mobile tech demo (literally a tech demonstration) out on Android that just shows off the effects it produces on any platform it can slather its effects on.
https://www.youtube.com/watch?v=iFceCt4YwCc
(I tried this on my old LG G2 years ago, BTW, it's not just brand new phones pulling this off, the demo is from 2014.)
OROCHI is their game engine/development suite, like Renderware or Unreal or what have you. (I believe it is only available to license for Japanese-speaking game development studios?) World of Final Fantasy was made on that, Valhalla Knights 3, the upcoming City Shrouded in Shadow (strangely, lots of Vita games on their clients page, but focus on the console versions of those as obviously Vita can do bare minimum with it), Rise of Incarnates, and others; I believe 3D Dot Heroes was probably the pilot app for the engine, and it certainly was the calling card for both OROCHI and YEBIS.
XENKO is a new engine that is described as their next-gen tech (open-source "Next-Level C# Game Engine") with physically-based rendering and low-level API access and VR support. I don't know much about it, I don't think anything's been made professionally on it yet? It's targeting all platforms, from PS4 and beyond down to mobile (in fact, the only gameplay demos in the
XENKO trailer are very simple phone endless-runners.) This also appears to be Silicon Studios' tech for global release, as even the Japanese website links to the English-language site for XENKO. As Kent said above, you should be able to actually download the development tools and play around with XENKO yourself.
http://xenko.com/
And don't forget about MIZUCHI, the company's next-gen "rendering system" (which is NOT listed for Switch... Hmm?) This is the thing that's been wowwing people at trade shows for a little bit now, with that crazy-looking
Museum demo. The GDC 2017 tech demo showed off some applications outside games, including architecture and car concepting. Fun stuff, but as far as games, the only title I can see that uses it is a pedestrian-looking
Square Enix Japanese PC/PS4 F2P(?) game called Figureheads, and it's been showing about town for a few years now (and it isn't pledged to Nintendo Switch yet,) so temper your expectations.
https://www.youtube.com/watch?v=br0ZrbSvmoE
...Keep in mind that lots of these technologies cross over and get intertwined, so you'll see a game using YEBIS lighting but a different engine or YEBIS and OROCHI engine together or YEBIS lighting on MIZUCHI rendering, etc.
And as with any engine/technology, you can't look at the very best stuff and go, "Oh man, that looks mind-blowing, this is going to look awesome on Switch!!" because you never know what will actually be made of or be possible with the tech on the platform. In general, though, this is very good news for the platform. expanding on expectations already set by the announcement of Xenoverse being made for Switch and Octopath Traveler being done for it by Silicon Studio. It's particularly good to have this Japanese company on board for Nintendo's platform, that could be a fruitful relationship.