I'm sorry, but signal is absolutely not discord replacement. It covers maybe a third of what discord does well. It's a features issue.
Revolt is the closest in terms of ui and function, with matrix being slightly closer than signal in terms of working the way a discord user might expect, but still not as close as revolt.
Heck, teamspeak and mumble both have android apps, and would likely be better than signal specifically for gaming and casual chats. Since desktop signal can be iffy, at least those options cover three out of four platforms (no idea if there's iOS/mac apps or not). Disclaimer is that I've never used either on Linux, just know that they have options for it.