If you build a single dataset without any visuals and publish it to the service you can then delete the empty report part and be left with the dataset. You can then connect to that dataset in power bi desktop and create "thin" reports that all use the single dataset.
If the reports already exist...
1) Save backup copies.
2) In transform queries delete all the tables.
3) Delete any calcualted tables (Check for any hidden tables).
This will look like it's broken anything but if you then go get data... from power bi dataset you can connect it and it will all work.
There are many ways of going further than this. We have a Models workspace which has our enterprise model(s) in and reports are then in other workspaces. As long as people are given read permissions on the dataset they don't need to be viewers or members of the model workspace it self. You can also grant build permissions to the dataset.
Finally since you have premium you can also build your initial model in power bi, publish it but then edit it within the service by connecting to it via XLMA endpoint with tabular editor (2 or 3). We use deployment pipelines so we can develop within the service without risking the production dataset.
If any of that is of interest I'm happy to go into more detail.