Hi
TLDR: First time owner, 5 old month B with what seems to be separation/confined spaces anxiety, is doing better with lots of training and trial & error.
First time owner here as well. We've had our boy for close to 6 months now and it's been a hell of a ride. First month is pretty much the hardest, after which it gets easier. But for that to happen, training is mandatory with each and everything you do with him, including alone time (well, obviously, as others have stated to me here, he is a puppy, he needs to feels safe, be with you etc, so by training I don't necesarily mean going hard on him)
We are in a similar situation, where me and my fiancee WFH, and leaving him alone has been quite a process so far. My first advice would be to start as early as possible, as I believe we got to it a bit too late (at around 4 months we actually started really working on leaving him alone). It's probably never too late and fine while he's a puppy, but earlier might be easier.
Second, would be crate training right from the start and stick to it. Even so, he might hate confined spaces, in which case leaving him alone in the crate for hours will probably cause more harm. Ours is fine with it (sleeps in it sometimes, by his will, at night by ours; goes in by command, stays there as long as I want him to, even if we're not in the room) but I believe he hates confined spaces, which is why we started leaving him alone in the house (he has access to the main room, hall and kitchen) and with that he has progressed way faster.
3rd and probably most important, things to have him occupied. We've got at least 1 frozen kong ready at all times, to be prepared for any sudden leavings. But that' the main thing that keeps ours busy. A kong stuffed with moist kibbles and topped with something that he goes crazy about (chicken pate, soft cheese or, sometimes, peanutbutter). A size M kong lasts him for about 45 minutes, until he gives up (last kibbles are hard to get, he goes to it later when they melt). A fresh bully stick/beef tendon, we also hide 2 cups greased with greek yogurt and topped with small bits of freeze dried meat (these usually keep him busy for at least 10 minutes, because they slide on the floor tiles or they flip).
Needless to say that the last point has him focused for about 1h, which on itself is exhausting. Now, if you combine that with a 30-45 minutes walk right before, you got yourself a rather chill B. Our routine consists of a morning/mid day ~45-60min free walk through the forest and ~1h of play time with other dogs later in the day (having him run with a husky has been the most welcoming thing.. he gets home and drops). And 2-3 training oriented sessions per day, of course.
This has been my experience so far. We got from a point where he'd panic the moment he'd hear the keys, to a point where he goes into his crate when hearing them :)). He just loves his "alone time" treats now. I'm not confortable on leaving him without following all these steps (like an emergency leave), but fortunately we still have the time to work with him around our routine, which hopefully prepares him for future unplanned alone time.
I didn't expect it to be this hard, honestly, as none of my friends or family members that have dogs had similar issues, but if you have the time to work with it, it's worth it. I wouldn't trade my B for any other breed.
