You can now achieve 12–14 hours of playback (FLAC, screen off) versus the stock 8–9 hours.
The NW-A105 does not have an official method for unlocking the bootloader. Without an unlocked bootloader, you cannot install a custom recovery (like TWRP), and without a custom recovery, you cannot flash a new operating system. While there have been isolated claims of exploits in niche developer circles, there is no "one-click" solution or publicly available method to root the device safely for the average user. sony nw-a105 custom firmware
Sony abandoned the NW-A105 for updates. It will never see Android 10 or 11 officially. However, the CFW community is working on a custom LineageOS 18.1 (Android 11) build. You can now achieve 12–14 hours of playback