Mozilla can model itself after Microsoft somewhat.
Provide a development stack (they're experts at Web and Rust). Make themselves the go-to shop for developers in that realm.
Sell them on an OS and editor with support. Partner with Ubuntu. Hell, I would even reach out to Nadella and see if they'd be willing to work with Mozilla on hedging against Google. Mac is becoming locked down and kind of unpleasant to develop on/for. Mozilla could win this.
Block all the advertising and tracking. Build a Spotify-like news aggregation service you can access from your Mozilla subscription.
Build an email service like Hey and a file backup service like Dropbox. It's too bad Zoom bought Keybase, but perhaps Chris Coyne wants a new gig?
We should team up to beat FAAMG. Most of the FAAMG actors are actually quite damaging to open source despite benefiting from it greatly.