They are web apps... open.spotify.com, discord.com, app.slack.com. Even vscode.dev. The desktop product is just a repackaging of the web app with perhaps more OS integrations. If you don't want the OS integrations, use the web app. Some are available as a PWA too, which provides a nice middle ground.
They all have artificial restrictions in the web versions which makes them worse to encourage people to install the apps (actually not sure if discord does this, I've only used it a little bit). For spotify and slack there is definitely an active push to make their web apps worse than they need to be.
At least for VSCode, it's the other way around - the app was first, and even if it was always an Electron app, it was still designed and written for the desktop. It actually took some time and effort to port that to vscode.dev, which wasn't there at the beginning.
