I bought some basic pants for work from Uniqlo at Ion and tops from H&M orchard. Other than that, I just bought stuff that I believe I’ll also wear postnatally. I like the loose Korean dress top styles which are all maternity friendly too.
I just upsize normal clothings. Eg instead of S, I would size up to L to accommodate my growing bump. But I would advise to just go for oversized Tshirts, at least you can still wear them after birth (after you shrink back).