Tested devices can be found under the link: https://android-hotspot.de/en/1300-2/

The app launches the hotspot as soon as the matching Bluetooth device is nearby.
The function can be switched on and off.
No annoying menus. Everything is visible on one page.

Differences between the Pro and Free version
free:
Works with only 3 Bluetooth devices
Pro:
Works with unlimited Bluetooth devices