What OS are you going to use on your Smartphone if you remove software from Google and Apple?
People in the FOSS community constantly talk about the best ways to minimise use of Google, Apple and Microsoft products. That is an absolutely valid motivation for choosing to use one project over another.
If someone is willing to use the behaviour of a company or its owners as a factor when choosing a software stack, presumably it’s valid to apply the same sentiment to development teams of smaller projects too.
You’ve pretty much just described ActivityPub and the Fediverse.
Anyone can spin up their own instance. You can self host on a machine in your house, or with any cloud provider. You can broadcast messages in Twitter-style or Reddit-style format. Anyone can navigate to your web address and see your messages. Anyone who federates with you can see it on their website. FOSS Android apps are available.
You can’t force anyone to actually read your messages of course, but that’s a different matter.