Use Hue Tap Dial Switch without Hue Hub?

Yep. It’s on the list of edge drivers for remotes:

https://community.smartthings.com/tag/edge_remotes

Specifically:

[BETA][Edge Driver] Hue Dimmer Switch / Hue Wall Switch Module (No Hue Bridge)

That one works with the rectangle and the inwall module (model 571166), but not the circle.