You might be able to backdoor your way to doing this, if you save a file to sharepoint, then part of the instructions is the receiving user has to "save" the document, you could then have another flow that triggers on when document is created or modified.
Otherwise I can't think of a solution. The information has to be available at least within O365, as I can see on sharepoint that so and so viewed this document or that, I just don't believe that information is currently exposed in an API.
Try submitting the idea here:
Power Automate · Community