Just stepping in to this.
Have you tried sudo dnf install steam --allowerasing ?
That may fix the issue.
I have installed steam on both Fedora 34 & 35 and both work well when installed from the rpmfusion repo.
Looking at what you have posted I think this is likely the clue and fixing that would solve the install issue.
package libnghttp2-1.45.1-1.fc35.i686 is filtered out by modular filtering (try to add ‘–skip-broken’ to skip uninstallable packages)
Have you looked here? It may have the solution for you.