Now if you edited the DNG in Lightroom and exported a TIFF instead, and replaced your DNG with the TIFF - then yes, absolutely, that's an edited photo and a lot of changes have been 'baked in'.

(Note I use this as an example but do not know if it is true, I've simply heard it). NOT because it has been edited (in the sense the image has changed) but because the structure of the DNG file is not understood properly by that program. Now if you took that DNG and tried to go to (rumor has it) DxO's editor, it might not work. So long as it can fully process the DNG then the fact you imported it to Lightroom, or even converted to DNG, is moot. This is a non-destructive process at this point however - if you take the same DNG and go to (say) CaptureOne, then it will ignore the preview, and start with the same raw data (not yet edited) and do it's proprietary conversion to color, which may result in a slightly different look than LR.

This must happen to view the image, every raw editor will do it, they all do it differently. It is fair to call this editing, even if automatic. That process converts the raw data to a typical color image it is sometimes called a de-mosaic process. Now as it comes into Lightroom, the image produces a preview. For lightroom the theory appears true, but if you later tried using a different editor you might not get the same results, but (I believe) because of the meta data, not because of the image data. In theory that does not change the actual image data. During the DNG conversion that data is changed, and some may be lost. First caveat: a digital image is more than the actual counted photons that produce it, it is also a ton of metadata that describes how it was taken, including information about that capture's structure. When you imported a CR2 into lightroom and, during the import converted to DNG, that is primarily just a change in file structure, and not a change in the raw data. There are subtle aspects to your question I'm going to try to be careful about, terminology is a bit tough here.

Lightroom vs dxo photolab 5