It could then use IPFS to host "Public Facing" posts. People could pin - or pay for pinning - their posts.
IPFS is what I hope will lead to further democratization of the internet.
I am aiming for a decentralised-FB like experience on Signal. And I honestly think it is feasible.
On FB, you tag a post with intended recipients(default:All "Friends"), people log in and get fed these posts with FB fiddling along the way.
Signal with a redesigned UX could show a doom scroll of posts that friends send you. Not that I think this is great, but user adoption for familiarity.
Signal E2E delivers the message, the new UX displays the posts. You apply heuristics as you want, all without ads or data gathering by a MITM.
But... public posting is a thing. I am hoping that IPFS combined with cryptographic signing for authentication, could fill that role.
Hence my comment that IPFS could hopefully lead to democratization. Although, I am also concerned that IPFS will also lead to "undeletable" content, but that seems to be almost a thing anyway.
There's also cabal chat which is based on the same underlying technology but is chat focused rather than Facebook like.
Filecoin is a separate thing (mostly), and can (kind of) be thought of as pinning-as-a-service. It's built on a private IPFS network, not the main public one most people use or are directed to. So it's using IPFS, but it is not IPFS.