Sharing DAC apps is subject of the App developer permission roadmap issue:
Currently only a single user is recorded as the ‘owner’/‘developer’ of a Forge app and is the only user who is permitted to perform actions such as deploying, tunnelling or viewing logs for the app.
We are planning to enhance Forge so that the developer may grant permissions to other users for their app.
We consider solving this limitation a blocker to providing support for commercial Forge apps via the Marketplace.
Once this is in place, we’d probably base any published app of an “API account/bot” indeed (would not be required if there can be multiple owners). This would reduce the problem to the DX for overwriting the app ID when working on per developer environments.