Morning/afternoon baths. Baths anytime.
Watering the plants
Sleepy drives at nap time, find a nice cafe that does take out and enjoy those blissful moments of silence.
Baking/crafting - doesn't need to be complicated, at that age mine just loved cutting pics out of my old magazines and sticking.
Big play (DH can do this, make dens/build camps, obstacle courses etc, the stuff that takes some big moving of stuff)
Have you tried the larger Hama beads? Might be a bit young but DD would spend ages doing these at around that age.
Scavenger hunts - go and find me three odd socks, two red things etc. You put your feet up and collect the scavenged items. Prize at the end.
Drive to see anything, local airport, train station, building site, forest etc...
Small errands, going to the post office etc - admittedly harder with Covid, but giving a walk purpose, 'must post nanny's Christmas card', makes them more engaged and cooperative.
Play doh. Not too messy. I can't bear messy play. Not with SPD.
I feel for you OP I really do. It is a trying age, and SPD is miserable.
Things to feel positive about;
By the time your baby arrives we should be on our way out of this and heading into a brighter spring.
IME SPD all but disappeared overnight after baby came.
As PPs have said, it will pass, you're in the thick of it now, but it will. Promise.