Second, strip the DRM using Calibre, and store the books off any cloud-based platform and on your own drives, as you always should in any case given the proclivity of many content companies to just flagrantly bullshit their way into excusing themselves when they frequently steal back their customers access to stuff they ostensibly own.
Once a piece of digital content is actually yours, in your own device drives, it's only then really yours.
Keep the on-device cloud-based versions around if you like the user interface of your platform or reader, but your own digital copies elsewhere. The retailer doesn't even need to know (though I personally wouldn't give a tin shit if they did anyhow).