So what I think you're talking about is called deep links, and it's certainly a challenge in this scenario

I'm pretty sure it's solvable with some effort, I'm working on a Lemmy client now and will look into intents that could be sent from the Lemmy front end. My main concern is just recognizing the links in-app robustly as people learn how to format them - if the client doesn't kick you into the browser, it solves half the problem and I'll worry about the other half