The mechs would not be natively produced, acquired through the usual means of salvage or purchase. Good chances to justify all my custom urbies too, put together as field refits from whatever parts have been scrounged. Combat vehicles, maybe something could have been produced but those could be much the same.
Infantry equipment, yes for native production, that seems supported by the lore. Battle armor, probably not, but they could likely have bought some of the cheaper variants. They'd be a mercenary company operating inside the Inner Sphere, just from the Jarnfolk. I'm thinking maybe a custom jumpship without a sail or a dropship too, as Jarnfolk build both. Maybe one of the nine clans is using them to try and train up a military force to make a play on taking control, maybe they're just a business venture. Thinking one specialized in defensive contracts, anti-pirate work, garrisons. Slow mechs, combat vehicles might be faster. VTOL even perhaps, the Jarnfolk are apparently good pilots so that might be justified too.