Unfortunately, Android devices cannot act as iBeacons without heavy low-level modifications. See here.
The answer above is for Android phones, but the same obstacles apply to a mini PC. Connecting an external Bluetooth dongle is just the first challenge. You would then need to overcome these hurdles:
- Root the device
- Write and install a driver for the Bluetooth dongle
- Install AOSP custom ROM to enable Peripheral mode support.
- Write code to make the device send out the standard BLE iBeacon advertisement.
This is probably way more than you want to bite off!