These days everything goes thru a computer. My ex's 2015 Canyon had no AC. So she had my son ask me to look at it. For him, yes. Her? Pay the man.

Anyway, turns out the battery was iffy. Put my code scanner on it (hint number one for the OP) and it was telling me the HVAC computer was seeing low voltage (11.3V). So I did an engine off test of the battery voltage and it was about 12.2, which is low. Asked her about her recently driving to see if maybe the charging system didn't have time to top off the battery. It did, or should have, so I had her fire it up to measure the charging system output, 14.4, which was good. Then se says "hey the AC works" Me jut jamming my probe tips in between the battery post (no more side posts on GM's apparently) and the battery clamp made it work. Terminals weren't shiny, but there was no corrosion either. I suspect a good cleaning would have sufficed but the low voltage on the battery without the engine running made me suspect it was on the way out. It was a bit more than 3 years old and I had to replace the original at about that time frame too.

Near as I can figure the vehicle does a computer(s) system check before it turns on the charging system when you first fire it up and since the HVAC computer saw voltage below it's minimum it wouldn't turn on. I know it's a GM but I have seen similar issues on other late model cars caused by this. Heck my 86 Daytona had a problem where everything electrical BUT the engine would shut off. Be driving down the road, hit a bump, engine stayed running but the rest of the electrical system turned off. New battery fixed that.

Might check your battery voltage, engine off, and see what it says. Clean up the posts and terminals so they are shiny and see if that helps.