We have a dog. We got him as a puppy, I was at home with him 24/7 for 3 weeks and then went back to work. I did half days for about 2 months where he was left for 4 and a half hours a day alone.
At first we left him in 'his room', no soft furnishings, his crate and bed, lots of toys, pee pads, food and water. Then started testing him having access to the kitchen as well, gradually adding more rooms. Eventually we were able to leave him have free roam of the whole downstairs which he much preferred snoozing happily on sofa.
I then went back to work full time, he was alone for 4 hours, then had an hours walk (by dog walker) and was then alone for another 4 hours. At first he struggled with the extra 4 hours and we had chewed furniture, so we'd give him free roam of downstairs for the first half of the day, then the dog walker would return him to his room for the rest of the day. After a few weeks of him getting used to it, he was back having the whole of downstairs.
He was fine. He doesn't have seperation anxiety. He's a happy chap, and because we did it gradually he only seemingly had a few days of distress. We got lots of toys that interact with him throughout the day, e.g dispensing food every half hour etc. We leave the radio one and did have a puppy cam so we could make sure he wasn't distressed. We now never have to worry about popping out for a few hours.
I am only part time again now and will be off on maternity leave so he's got me back which is nice but he has turned out fine. So many people will say "you don't know that" etc and try and make you feel like your dog is distressed and mistreated and MN LOVES telling you to return the dog to breeder/rescue (I was told many a time at first)
The reality is many (if not most) dog owners work full time. Yes it is a large reason dogs end up in rescue, and yes some people take it too far, leave dogs too long, don't think about the dogs well-being etc. But a large amount of us also work full time and find a way to make it work so the dog IS happy. Its possible. It's not always easy and yes it's heartbreaking when you get home and see destruction caused by a bored or distressed puppy - but learn from that. We came home to it and instantly started trialling new things, new toys, new timings for the dog walker. Eventually we found something that worked.
MN is the worst place I've ever asked for dog advice as they seem to think unless you are at home 24/7 you are a terrible owner, your dog must be distressed and you must return them immediately. Bullshit!