You can buy lockpicks from nomad trade centers. There is one north east from the church at the Grove Street residential area.
You will find seeds inside attics, house basements, if you follow Maggies story, you will go to a garage to get some blueprints. Next door is a Bisonal Gas station with a dead nomad, and a locked door leading to a room with shelves with plenty of seeds.
Getting Thermo Drill to level 2 will allow you to drill the icebergs around the Void, inside the containers are more seeds.
There are plenty of locked doors and cabinets, inside Gas stations, Hospital, the Tech company Christophe's story ends at.
You need to lockpick 20 locks in one game.