If you want to 'protect' FOSS projects you care about, take some time to find out what help is useful to the maintainers and contribute towards items that make sense to you. Joining OSI won't help those struggling projects you gain from using.
Indeed, it is an incredibly rewarding experience. Take one thing you use and like, go to it's issue backlog and start fixing/improving things - if there is nothing take the next thing, there are likely 10s of thins you rely on every day that need contributors and contributions. The first issue will be hard, the next one easier, you will be a happier person for doing it, you will make a bigger impact than starting another project you won't finish and that nobody will use, and you will become a better engineer.
Another option is to fund actual open source projects, like go sponsor python: https://github.com/sponsors/python
As a service provider I want to make money. All it takes is a reasonable commitment to distributing a portion of the revenue I capture to provide a lot of these projects with more money (assuming of course I’m a success, if I’m not they’re probably no worse off).
In my admittedly naive opinion all that stops this from happening is that no one has taken the long term view and been willing to eat into profit margins. I want to see if I can change that.
Of course money is not the only thing projects need but it can often ease worries of maintainers and be leveraged to purchase resources.