The suit does not claim that iPhones have a monopoly on the phone market - it claims that Apple has monopolistic control of the app ecosystem within the iPhone market.
Their monopolistic practices are, arguably, preventing other monopolies. If Safari disappeared 97% of mobile browsers would be Chrome (or use the Chrome engine):
https://gs.statcounter.com/browser-market-share/mobile/world...
Chrome has plenty of anti-competitive practices that aren't under scrutiny. Nudges in all Google owned software to switch, breaking features in other browsers (Firefox Whoops).
Like, I guess I'd be way more "pro this lawsuit" if Google was under similar scrutiny.
You and I can feel whatever way we want about it, it doesn't change a thing. Apple's market abuses are unique from Google's, and specifically you are asking the DOJ to punish Google for abuse that hasn't happened. Google's most egregious violation so far has been their advertising racket, which they were already punished for last year: https://www.reuters.com/legal/us-wraps-up-antitrust-case-aga...
It still seems quite distinct as users aren't forced to have an iPhone, there are widely used alternatives, but folks were forced to have a PC if they wanted a computer for most tasks and situations back in the 90s.