This will definitely be implemented at some point!

I would love to be able to filter by series and then by books I own OR don’t own in the series.

100% yes. I've started reading more ebooks but I still like to buy a physical copy of some of my favorites. Having a way to categorize all my owned books my format would be beyond helpful.

I came here just to reinforce I'd love this feature. As a mood reader, I organize my physical unread books on a separate bookshelf so it's easy to go there and pick what I feel like reading next. To replicate this, I'd love a easy way to filter and look at all my unread owned e-books on a single place and the ability to filter owned books by format would do that.

Would really love this for the "Read" list as well, not just TBR/Owned. The workaround mentioned in an earlier comment has no way of sorting the books 😭 so if you're trying to create a tag of books of a certain format in the order in which you read them, you have to scroll through your entire list, examining each book to make sure you're picking the right formats.

this!!! i get so many free ebooks but i don’t really want to see them with my physical library. but it would be nice to keep track of them outside of kobo

This would be so handy - when importing from THAT OTHER APP, a quarter of my books came in as audiobooks. Would make it a lot easier to track them down and fix them if I could filter by format :)

This will definitely be implemented at some point!

This would be so useful! I'm trying to work on my digital TBR, would love this filter!

There is a roundabout way that you can do this. If you go to your stats and change it to show "all time" on the right hand side it adds another pie graph of format just for TBR. It's not optimal but it work around if/until this gets implemented