Apple hardware wise for smartphones in q4 2023 according to counterpoint research has a 23% market share. Slightly above Samsung. So if that is your definition of dominant…If every vendor's distribution of Android is different than the others then Apple has the majority of the market share at 34%, followed by Samsung at twenty-something % and then other vendors.
(Your premise is flawed, you can get from every distribution of linux to any other by changing the installed packages since Linux (the kernel) itself is the same)
Apple is being penalized because smartphone manufacturers buy their operating system for $1 instead of devoting $$$ into r&d. it’s a fake duopoly.