From the official Eclipse downloads page as of 10/31/21 there aren’t any M1 builds ready for download. However, following the comments on this bug/feature request, there have been daily builds for M1 it looks like for some time. The daily builds are available here.
I downloaded the latest stable build from here:
Double-clicking the downloaded .dmg and then dragging the Eclipse app into Applications is all that was needed to install. Done!