True. all-the-icons.el has some links to other freely licensed sets.
Could one of them be a suitable replacement?
All-the-icons uses fonts to "bundle" the icons, which I recall some people dislike, but we could extract them. Here's a link to the details of those fonts:
That takes you to Github, so here's the relevant data. (I tried to use the eww render, but it lost the links.)
All of the fonts provided in this packages as resources come with either the SIL Open Font License (OFL) or an MIT License, below I will link to each of the fonts Sources and their Licenses.
Hope that helps,
~Chad