STEM approved while awaiting H-1B lottery

AD/PP/VSC/Only ONE petition
(2nd time, didn’t get through lottery last year)

Applied for STEM about a month ago, my STEM-EAD got approved yesterday.

Does it mean my H-1B got picked?

EAD and H1B application are both different. Your EAD approval will help you work in USA on OPT, once your EAD expires you will have to leave the country unless you have a valid H1B approved. You need to check with your employer, who applied for H1B visa regarding the status of your H1B application.