I don't think that functionality exists for Backdrop's Feeds. Best way to find out is to post a question in the Feeds Github issue queue, so that the maintainers can respond.
I have had a read of what Lando provides, and it's an excellent development tool, and it would solve the problem.
But, I would prefer to find out why the problem is there in the first...
You might need to add a Relationship in the View to Flags. Or there might be a setting on the content type. I can't recall for certain but I think it's possible.
Comments
I've never imported comments with Feeds in D7. How do you do that?
Never done it in Drupal7 either, but from D7 to D9
I don't think that functionality exists for Backdrop's Feeds. Best way to find out is to post a question in the Feeds Github issue queue, so that the maintainers can respond.
https://github.com/backdrop-contrib/feeds/issues
An upgrade from D7 to Backdrop will include the comments by default, unless you have opted to do a migration manually instead.
If so, have you tried Migrate?