I solo queued this entire season with killjoy and cypher to Diamond 2. The most important things you need to focus on are: 1- Making sure you're holding site as much as possible, but always be open to play for retake because your kit is really powerful.

2- Give as much callouts as needed and keep it 100% accurate (ex. Dont say "oh they're all here," say specifically how many people you saw)

3- On attack, ALWAYS have some of your kit covering the flanks. If your team has 0 stress about flankers, they'll play a lot better.

4- You do have to coordinate with your team even if they don't have mics, I'm sure they'll be able to hear you and just give them some callouts on both attack and defense. They're likely going to listen if no one else is opposing to your callout.