[trevcanhuman]

I've used Weylus [0]. It works over LAN, lets you control the mouse from your tablet. Sometimes it's laggy, but you can configure the resolution so it's not using too much bandwidth. I'm not sure if it's stable at all. Haven't used it on a regular basis.

[0] https://github.com/H-M-H/Weylus

[DakotaR]

In the same vein, Remote Touchpad [0] is fantastic if you don't need an extra screen.

[0] https://flathub.org/apps/com.github.unrud.RemoteTouchpad