Some feedback: I would also add dedicated buttons for downloading MacOS and Windows binaries - for typical users gitlab button will be to scary. Website also not clear if there is and SDK for developers (the one that supports also airplay and chromecast) and what languages bindings it supports.
A SLSA Builder or Generator can sign packages and container images with sigstore/cosign.
It's probably also possible to build and sign a repo metadata index with GitHub release attachment URLs and host that on GitHub Pages, but at scale to host releases you need a CDN and release signing keys to sign the repo metadata, and clients that update only when the release attachment signature matches the per-release per-platform key; but the app store does that for you