According to M-W, you can:
1 : having the same nature, disposition, or tastes : kindred <congenial companions>
2 a : existing or associated together harmoniously b : pleasant; especially : agreeably suited to one's nature, tastes, or outlook <a congenial atmosphere> c : sociable, genial <a congenial host>
But... I personally wouldn't because most people will be more familiar with the second definition above. I might use We're kindred spirits -- a cliche, perhaps, but then cliches are readily understood.