Determining true bug larvea to the species level is tricky and rarely done. But with some experience, it is possible to tell the families apart. Seed bug larvae have elongated, rather flat bodies of brownish colors (which camouflage them on the ground where most of them dwell). Often, they have a pointed nose (a long head) and relatively large eyes.
From their habitus, they could actually belong to the genus Nysius (you could compare with Fauna Europaea which species occur in your region).
But they could also be another species from the seed bug superfamily.
Moreover, identifying Nysius (and most other seed bug) species usually requires a microscopical inspection.