That's a good question.

Tiling managers are a must. They're part of the desktop environment. I've been running one since Compiz/Fusion almost 20 years ago. Compiz features are what all these modern desktops seem to be copying.

Librem phones run the Phosh desktop/mobiletop on Mobian OS (Mobuan = mobile Debian). I'm not sure if Phosh offers a windows tiler. 

 It's Linux that means you're not restricted. You can switch OSes and desktop environments. PureOS, Mobian, postmarketOS. Phosh, Gnome, KDE, SXMO. I'm guessing at least one of them supports tiling. Gnome on desktop does through an extension I use called tilix I think.