The hardest part of this lawsuit will be determining the remedies.
There are several issues at play here but I don’t think determining the remedies would necessarily be hard. They could include things like allow sideloading, alternative app stores, alternative payments systems, alternative browser engines, etc. Allow greater interoperability between Apple and Android devices. Limit pre-installed apps and/or make it possible/easier to uninstall apps. Make it easier to change default settings.