I’ll start with saying boots/footwear aren’t considered bifl to begin with. That being said, steer clear from anything vegan leather. They will wear down faster than the soles and will not be repairable/resoleable, which defeats the purpose of looking for non leather welted footwear.

Aside from buying second hand, I doubt any companies are using recycled leather. I’ve only heard of one instance thus far that has used hides from naturally deceased bears found in the forests of Japan from John Lofgren. And those were sold in tiny quantities and are doubtful to show up again.

If you’re looking for the least environmentally impactful leather, go for a veg-tanned leather. They’re still made from cow or horsehide, but will decompose a hell of a lot faster than anything chrome-tanned. Even better, look for brands that are small, independently owned, and great only a small number of boots a year. That way you’re not contributing to any waste that the big companies produce for unsold products.

Check out r/goodyearwelt for brands. Cheers.