feature request: mark and diff files in the oil buffer

[duemir]

Did you check existing requests?

• [x] I have searched the existing issues

Describe the feature

I would like to be able to somehow select a few files and use them to start a diff.

Provide background

netrw allows to mark some files and the press md to vimdiff the files. I've been using this feature, so wondering how can I do something similar if I replace vinegar+netrw with oil.

What is the significance of this feature?

strongly desired

Additional details

No response