@jnbrgr
Us adding extension support on mobile independently is a rather unfeasible task. It's one thing to implement it, but maintaining support Chromium update after Chromium update would likely be a near impossible task.
Out of curiosity, which extensions would you like to use in Vivaldi on Android?
@Vivaldi Thank you for your answer.
Requested mobile browser add-ons would be Bitwarden, uBlock Origin (built-in functions in Vivaldi don't work as well) and Privacy Badger.