One exception I’m aware of: GNOME Web (aka epiphany-browser) uses WebKitGTK, which is based on Apple’s WebKit rather than Google’s Chromium/Blink. But it’s Linux desktops first and foremost. Not on mobile platforms, not exactly intended for Windows (might be usable with Cygwin/WSL) or macOS (seems to be on MacPorts) either, and even on non-GNOME desktops like KDE it might seem a bit out of place.
I daily drive Firefox but Epiphany is my first choice fallback on the rare occasion I encounter a site that’s broken on Firefox.