Nintendo is launching Mario Kart tour on mobile September 25th and pre-order is available. Mario Kart Tour launches on iOS and Android and from some early impressions seems to be a fairly simple take on the Mario Kart formula. Not sure this will replace Mario Kart 8 Deluxe on the Switch but if it's fun, i'll play it. These Nintendo mobile free titles haven't been great but if you don't have a modern Nintendo system and don't mind simple fun, they aren't too bad.

https://mariokarttour.com/en-US