My allergies are worse in summer @VanGoSunflowers , I rarely have asthma symptoms through winter although I can still occasionally get reactive to both Brie & Freija with tingly mouth and tongue, itchy ears. I wasn't too bad with Brie this year overall, because her big spring/early summer moult had finished by the time my seasonal asthma kicked in. I do use a steroid inhaler twice a day though so I suspect it helps to minimise what I do get. The only advice I can really give is to try to give a daily brush to get the loose stuff out and do it outside, if you can. I put a buff over my nose and mouth when I groom. You may find it's better when his full adult coat comes in next year but I know it's worrying, especially as he shares your bed...It sounds like you need a Ventolin at least for that early morning tightness. A hot drink always helps me.
As regards exercise: we were probably doing less at that age but ours is a low energy breed and all on lead so I'd imagine what you're doing is fine. I'll let the Lab people advise how much is right for Pablo, but trust your instincts, they've been good so far.
The best harness I've found is a Haqihana one, but I need quite a minimal design for Hairy Mary, so it may not necessarily be what you'd want for Pablo. The quality of it is amazing though. I use it with an Ezydog checkmate collar and a double ended training lead for ultimate control of my 55kg chunk.
As far as jumping up... nightmare! Brie is terrible for it. Everyone that wants to pet her gets paws on shoulders, so we really have to be careful around kids and older people. We've tried so hard to stop it but doggy people get such a buzz out of an almost 6 foot tall dog looking them in the eye that it's an ongoing battle trying to discourage it. That's where the harness really helps me. I just hang on for dear life to stop her flinging herself, but honestly, there is no easy solution to the jumping up, especially with larger dogs, and people's reactions don't help. You mostly get "oh, it's fine!" 🙄And it really isn't. Since winter weather kicked in it's become "Pet the Polar Bear" every time we set foot outside, so it's hard work at the moment.