We can make footwear from textiles, so that covers a part.

And for leather, it would probably be worth it investing in clean tanning and leather processing. It will be a long time before everyone gives up beef & co, so we will have raw hides for a long time. We might as well accept this and use a wonderful natural material that could save us a lot of CO2 emissions, micro and nano plastics, VOCs, PFAS and all the myriad other issues with second generation sytntgetics (polyester, acrylic, nylon, etc).