If you want native Kobo integration, alot of work has already been put into infrastructure:
https://pgaskin.net/NickelMenu/
https://github.com/pgaskin/NickelHook
This kind of stuff allows you to embed menu items and functionality right into the Kobo ereader where Pocket users are accustomed to seeing it. No need to switch to the KOReader environment, although that would have certainly been a nice alternative because of Its open source portabiliy and maintainability.
If you're set on a standalone app, there are also the rust-based Plato, and user Szybet documented a Qt app example.
For me, the biggest issue was the complication of a server, plus being a relative simpleton, I never attempted all that.
