Yes there should be some main wood supports above the drop ceiling panels depending where in the world you reside, all the track work that makes up your drop ceiling should be attached to those somehow, you could remove a panel and attach chains to something solid or beef up the supports & just hang from the T bars between each panel as long as your light fixture isn't to Heavy
those light supports in your link would work well as long as the plants & pots you use will fit under them
I can't coment if you can veg outside right now as I don't know where your from and I still have snow on the ground here