If you are using KOReader, then firmware patches are of no interest to you, since they are for Nickel. If you're comparing Nickel to KOReader, you can check the kobopatch repository on GitHub to see the various patches that are available.
The Libra 2 only has 512MiB of RAM, so you're not going to find alternative browsers for it. If having a capable browser is important to you, then you're limited to Android devices, such as those made by Onyx. You can, however, save articles to Pocket in order to read them on your Libra 2 later, without needing to use the browser. If you're motivated enough, there are also various ways to send files to the Libra 2 over Wi-Fi after converting them on a computer to bypass the browser limitations.
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