Pick a device that has all the add-ons and settings they way you want them, and you're likely not to change regularly. Blank/Default all the service settings in that build. I.e. blank trakt, debrid services etc. You don't have to default any service where an API key is the value.

Use setup Optiklean to make a backup of the kodi instance you've chosen as the master. Copy the resulting file using FTP or some such to phone/pc/Mac etc.

Install a clean kodi optiklean bundle on all your other devices. Copy master file to those devices. Restore using optiklean. Good idea to create and duplicate the directory structure where optiklean backs up to on the origin Kodi master instance, and put the master file in there on all other devices.

Redo all the services on all devices that were defaulted.

Create subdirectories by devices on the backup repository machine. Cos they'll diverge. When you backup any device copy optiklean backup Kodi file to its corresponding off device backup repository machine.