System76 firmware updates for older models?

I'm still running my Serval 7 using Lubuntu 18.04. System 76's firmware update utility threads just caught my eye; if I understand correctly they won't work for an older model like mine, correct? Google wasn't real specific about plans for older model updates; mine wasn't on the list of currently supported models. Is there a current list of System76 models with latest firmware available?

I came up with the same search results. Not owning a system76 I am no expert, but this seem to explain it.

https://news.ycombinator.com/item?id=17037845