Sidecar streams the mac display to the ipad, but it has to be initiated and controlled from the mac.

In contrast, what I wanted (what this app does!) is to view and control my mac from my handheld device, initiated from the handheld device.

These apps all look similar and it makes it very difficult to search:

• Mac screen --> Handheld, as extended display = Sidecar

Use-case: I use my ipad as additional window space for the mac.

• Mac screen --> Handheld, as duplicate display = Sill, Sunshine+Moonlight

Use-case: I leave my desktop and continue watching what I had playing on it from my kitchen ipad.

• Handheld screen --> Mac = Airplay

Use-case: I play some media from my iphone on the mac screen.

• iPhone screen --> Mac, controlled from Mac = iPhone Mirroring

Use-case: I use my iphone-only apps from my mac, wirelessly

• iPad controls --> Mac, controlled from Mac = Universal Controls

Use-case: I use my ipad with my mac mouse+keyboard

Usually, trying to search for this type of app obnoxiously returns results for Airplay, and if you manage to filter it out, it's Sidecar — but it's not what I want!