1. Raspberry Pi 5 boards are a small and well supported device for LE use.
2. I've never heard of Kodi being sideloaded on Roku things (but then I don't have any interest in Roku so..)
3. Android HDMI sticks are popular for running Kodi, if you like or can tolerate Android.
4. Android smart TV's are smart as long the the OS is maintained (sometimes yes, sometimes no).
5. You can run Kodi natively on modern WebOS (LG) TV's now, although it requires some developer mode hacking.
This forum is going to be rather limited to LE oriented ideas and opinions though. The more popular home for "best thing for Kodi" type threads is the the Kodi forum.