Do you have any green space locally? Doesn’t have to be a park specifically but a patch of grass/field would do? Take a bubble wand for little one to blow bubbles?
Would any friends close-by be willing to let you use their garden for an hour or two?
It’s definitely hard work entertaining a toddler at the best of times but particularly when you have no outside space.
I honestly wouldn’t put too much pressure on yourself either, there is this expectation when the weather is nice that we have to be outdoors all of the time but I’m sure your little one doesn’t mind a bit of downtime in the house. If you’re not feeling up to going out then I’d suggest not bothering and just taking the day to relax at home, it’s really important you look after yourself at this stage of pregnancy. I always find that painting/crafts go down well with my two