Hi and welcome to the forum!
I've never had any real problems with parts availability for my Husqvarna handheld equipment (chain saws, trimmers and a backpack blower) over the last 20 years. I don't know if that would apply to their mowers too but I would expect so. I did recently have to wait a week or two for a recoil assembly for one of my trimmers, but usually I get parts that that my dealer doesn't stock within a few days. Not sure if the ball got dropped by my dealer and they didn't order it right away or if it was back-ordered or what, but that was a rare exception.