Unfortunately, Android does not natively support applying the Private DNS settings to devices connected via hotspot. When you set a Private DNS on your Android device, it only applies to the network connections of the device itself, not to devices connected to its hotspot.
The devices connected to your hotspot will typically use the DNS server provided by the ISP of the hotspot device, and not the DNS server that you've manually set on the Android device.
If you want to force a specific DNS for all devices connected to your hotspot, you would typically need to manually set the DNS on each device connected to the hotspot, which can be cumbersome.
Another way around this would be to use a VPN service on your Android device that allows for custom DNS settings. Some VPN services will apply these DNS settings to all traffic going through the VPN, including devices connected to the hotspot.
Please note that the above information is based on the current state of Android and could change in future updates. Always make sure to check the most recent and updated information.
Phew. Good thing I'm not actually a machine!