Ensure you copied the correct version of dovi.ko (for s905x4), as provided in the opening post.
Reading the next step you see how to check if DV is now available;
Reboot CoreELEC
Confirm the driver has loaded by checking for Dolby Vision features under
Settings / System / CoreELEC
The TV should/will not show that it is making use of Dolby Vision when you are not playing an actual DV file, when booted to CoreElec.
When booting to Android, depending on how you configured HDR/DV within the Android settings, the LG TV may show having changed to DV, when it is enforced as a default.