What a dystopia.
This Google breakup is only going to destroy Mozilla entirely. Brave will survive as long as it can piggyback on Chrome development, and by getting bribed/paid by advertisers to have their ads shown instead of blocked. Ladybird can survive because it's all-volunteer, but it's not even close to being a viable browser for regular use, and with the limited development resources it has, it's questionable it will ever be really usable for general users.
The real winners of this "antitrust" action will be Microsoft (who can then dedicate more resources to Edge and make that the new IE6.0) and Apple. There will only be two browsers you can use in the future: Edge (Windows-only) and Safari (Mac/iOS-only). Other browsers will wither and die since you won't be able to use them for your internet banking and various other tasks. You'll just get a message like we did back in 2002, saying "this browser not supported, please install Microsoft Edge or Apple Safari to continue".
The justification seems easy - "fund us so your citizens don't need to depend on foreign ad companies and US-based tracking to access local and national services."
Make sure any parts which are dependent on Mozilla infrastructure can be re-hosted by other providers.
Have releases which are fully free software, with reproducible builds, which can be audited to ensure privacy protections.
And commit to legal agreements to preserve those protections.
The countries in turn can require that services in those countries must support Firefox, or perhaps specifically ESR versions of Firefox.
I know Schleswig-Holstein is moving to LibreOffice and believe some of that includes funding.
That I don't know of more is besides the point, which is have they tried?
They haven't lost their funding from Google yet, and the case ruling was only what? a week ago? Did you expect them to see into the future and predict this turn of events or something? I imagine they're very busy talking about this stuff right now, but 6 months ago they probably weren't too worried about suddenly losing their Google funding because of government action.