This is something I've started doing lately, making assets for streamers to use. Doesn't have to be on Twitch, but they are sized for Twitch.
Here's the big pack of all the Alert notification assets

Check out the rest of my Etsy page to see more, got a few different options for the assets, plus some I haven't talked about yet. I'm planning on making a bunch of animal emotes next so stay tuned! And if you comment what animal you'd like to see emotes and other assets for, you might get your wish~