Once you're added the sno seal, I don't really know if they'll accept dye (maybe/perhaps [doubtful, though,] spirit, NOT water-based dyes, and...they can't be dyed lighter than the darkest areas. I would not even attempt a dye job because it probably wouldn't take, and definitely (if it did take) would never be a uniform color because the worn areas would always look different than the non worn areas.
However, it looks like the soles (pretty worn, btw) are coming off in spots. There is a product called 'shoe goop' which is pretty good at holding/repairing soles coming unglued.
Bottom line, if I were you, I'd invest in a tube of shoe goop, repair the soles & wear your free boots till they totally fall apart. You might even use a dremel to add new, deeper grooves in the soles to give some traction, 'cause there isn't much there. (Personally, I wouldn't invest that much time in them, but I do have friends who would spend much, much more time trying to fix broken things than the things are actually worth.)