I believe the tag does allow you to post from anywhere, it even opens up the possibility of fundraising videos on dTube and dLive, etc. However I don't think the funds will get to you (at least automatically) if other people use the tag unless you've enabled "collaborators" on your project. I'm not 100% on how that all works...
The Fundition team is active and helpful in the Discord channel. I commented a bit about my interaction with them on your last update regarding the Fundition display not keeping the $ tally correctly.