The reality of the office upstairs being a living room for us for 8-9 months as we build is weighing heavily on its build. Little things like what instant water heater in the bathroom is best, small heater is also going to be inside bathroom. Wife wants some kind of pilates thing in a corner so having to plan on the appropriate heat for that (like the old Soloflex's I question how much she will use whatever it is).
This is like "deja vu all over again" for me. When we built the barndominium we're currently living in (1,100 sq. ft. in one end of the shop building), that's exactly what we said/thought; 9 months tops. Five years later, we're still living it in, though we see the light at the end of the tunnel now and might be in our real house by the end of the year. Your situation won't be as bad as ours, but the point is, building tends to take longer than you think and there are many things that can extend that time but few to none that will shorten it. So from my hindsight, yeah, you need to consider that you may be living in the shop longer than you think and build it out/equip it accordingly.
FWIW, we went with a quality Rinnai tankless water heater (propane) for our apartment/barndo that cost more than others but has worked super well and been 100% reliable; I will buy more like it for the big house.
My wife had to have a free-standing punching bag in our small space; I have never seen her use it yet.
To top it all off, I also have undiagnosed ADHD. When I was in elementary school, there wasn't even a name for it, but I was such a "fidgety kid" that my teacher and parents had me in some kind of therapy/PT for it. Fast forward to when two of my kids were diagnosed with it, I realized "hey, I have all of those symptoms too!".
In any event, all best wishes for your continuing shop build-out and house build. Love seeing your progress.