I know i have seen a vegan sporran, but sorry I dont remember where.

For footwear, I am sure there are plenty of vegan options. The one that comes to mind first are a pair of vegan 1461 Doc Martens shoes or 1460 boots. Not cheap, and not gillie brogues, but i think they would do, plus you can wear them other times, and personally i think 1460s go great with a kilt.

I am sure I will be corrected, but i tend to bend the traditional.