[rovingeye]

MicrosoftEdgeWebview2Setup.exe /silent /install

[debugnik]

I'm assume (wrongly?) that installing this dependency is managed by Steam before the first run, not up to them.

[zamadatix]

One can opt in to the common redistributables (which usually makes sense if the thing you're looking for is covered) or decide to package custom steps into InstallScript files https://partner.steamgames.com/doc/sdk/installscripts. In either approach, Steam will automatically manage the runtime dependency installation for the user before the "Play" button appears.