EMUI is a heavy skin. Custom ROMs like or Havoc-OS are leaner. Users report a noticeable increase in RAM management and battery life (up to 6-7 hours of screen-on-time) after switching to AOSP-based builds.
Before attempting to install a custom ROM, you must navigate the bootloader hurdle. Official methods are gone, so you will need: Nova 5t Custom Rom
I notice you've asked to "develop a feature" for a , but you haven't specified which feature you want. EMUI is a heavy skin