This a set of resources (reported issues, blogs, drivers, tips and tricks) to eager to use your Apple Magic Mouse in your Linux Ubuntu. These resources are recommedations of many people whom tried and got successfully the Apple Magic Mouse working in Linux. Next you can review documentation about how to configure it in your Linux PC:

Just mention that since Ubuntu 19.04 (kernel 5.0) the Magic Mouse works out of the box and not tweaking were needed.

In Ubuntu 19.10 I installed and uninstalled blueman, if you did that, you had to restart/enable the bluetooth service. Here that is explained: https://medium.com/@djorborn/bluetoothctl-failed-to-connect-org-bluez-error-failed-54040f12b4f8

chilcano@inti:~$ sudo systemctl start bluetooth.service
chilcano@inti:~$ sudo systemctl enable bluetooth.service
Synchronizing state of bluetooth.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable bluetooth

Finally I made the decision to buy the Logitech M590 Multi-Device Silent mouse instead of trying using the Apple Magic Mouse with Ubuntu 19.10 because I was getting scrolling lag, anoying behaviour with scrolling and clicking, and continuous bluetooth disconnection.

The Logitech M590 mouse can be use through bluetooth and unify receiver. It works in Ubuntu 19.10 and bluetooth by default, but not with unify receiver. To fix it I had to follow this information about Solaar and Unify technology in AskUbuntu forum: Is Logitech’s Unifying receiver supported?

I hope this helps you.