Cooks is gone, but there should be decent options on the FA market. Jakobi Meyers would be a reliable target for a young QB. Kenny Golladay and Allen Robinson will be released, and looking for a second chance.
I don't know what you're watching, but Johnston absolutely fits the profile (size, speed. RAC) NFL teams are looking for at WR. Metcalf, AJ Brown, Deebo Samuel. He may go before #12.
Collins looks the part, but he doesn't get separation, doesn't offer much RAC, doesn't get deep. Collins has good hands, but is little more than a big possession receiver. If he doesn't get better in year 3, you have to look to replace him.