Thank you for your suggestions. I went to a local Trek bike shop, and they told me that they could not find anything of the same size. They offered me a new Shimano crankset with an integrated spindle (I don't know what type it was). Total: $80 + labor. So I decided to invest this amount in tools and knowledge. I bought a bearing separator kit and 2 bearings. It was a fun project. It still works fine after 15 mi.

I wonder how to avoid problems with rare bike parts in the future? Should every single part be Shimano only?