You would be able to move to a generic CDS environment, if there are no dependencies on D365-specific components (from any app/module). Sounds like you're good there!
https://powerapps.microsoft.com/en-us/pricing/
Next up would be the licensing model:
- $40 Power Apps Per User "unlimited" Plan
- Would allow your users to use unlimited canvas or model-driven apps
- Has additional storage for entities and files, per User license
- $10 Power Apps Per App Plan
- We have explored this internally and confirmed with MSFT
- Access to 1 model-driven app
- Access to 1 standalone canvas app
- Access to up to 3 embedded canvas apps in the 1 model-driven app
The biggest considerations are expected storage usage, and whether or not you can get away with a single model-driven app for your purposes. Keep in mind, if you need canvas app functionality, that you will be able to license BOTH a standalone (non-embedded) canvas app, and up to 3 embedded apps (in the model-driven app).
You can vet your solutions by spinning up a trial CDS environment, adding a database, and then exporting/importing your customization.