Quest for a new simple 6-inch reader

[crAss]

Almost a decade has passed since I bought my Bookeen Cybook Muse Frontlight. I have read hundreds of books these past years and I really like the device.
First problem was the worn out sleeve, which I replaced with a generic one since I could not find an original one. Small issue.
Second problem is that the middle button in the bottom is progressively not working as intended. Instead of bringing up a menu it moves to the next page. Again, given that I do not read books in parallel, it is bothersome when loading a new book.
Finally, the battery has lost a considerable part of its juice. This was what led me to start searching for a replacement one.

Specs I want:
- 6 inch
- Black and white only
- Charge through USB-C
- Frontlight (warm light preferable)
- Hardware buttons for page change (old habits since the Bookeen Cybook Gen3 days)
- Full compatibility with Calibre. I have my library there and load books in my ebook.
- The lighter the software the better. I just read books on this one, using only bookmarks.

As I was going around I found just one ebook reader with all the above, the PocketBook Verse Pro (ok, the pro adds waterproofing not a deal breaker, but since I am buying one such device every ten years I do not care to spend a little more).

Are there any more comparable readers out there I was unable to find?

[DNSB]

You could also check the Kobo Clara BW though that lacks the hardware buttons. If you want compatibility with calibre, Kobo's ereaders are the gold standard there.