Here’s my take on it.
Puppies need to walk, to be able to explore their environment. The best way to do this is tethered to you, rather than in a sling of some sort. Does your company frequently see dogs on the floors? If not, I don’t see why he can’t be on the floor.
Use the crate more than occasionally. If you cannot have him tethered to you, he should be crated. I would also consider picking up an xpen so he has a safe space to play outside of the crate from time to time.
Frankly, I like the idea of taking him in to work right away, especially if you’ll continue doing that when he’s an adult. If you don’t intend to continue taking him in when he’s an adult, I don’t think I’d do what you’re planning, simply because he’ll wonder why you’re suddenly leaving him home when he’s older.
Is everyone neutered?
And no I vehemently argue that they “know better”. They may know you are not happy but they do not know spite or anger. I don’t recommend training on pee pads because it gets too confusing for pets. As I think is the case for your dogs. How are they supposed to understand “pee in the house, BUT only right in this little spot on this little thing?” How confusing must that be?
You could also try a belly band while you figure out how to manage the bathroom issues.