Are there alternative OSes for this very specific hardware? I mean, Juniper aside, the risk that other network gear is similarly affected as well surely is not

Are there alternative OSes for this very specific hardware? I mean, Juniper aside, the risk that other network gear is similarly affected as well surely is not zero, so I wonder if there is any FOSS (also as in auditable) alternative firmware for these devices, or any ongoing efforts to create one.