Reason: it is essential to build many things Google, such as chromium (browser), dartlang, etc. It might be helpful for a user who is building Chromium/Google stuffs, but it's mostly for our (the developers') convenience so that we don't need to git clone it every time we build a package developed by Google.
License: distributable, but I don't think it's open source: https://chromium.googlesource.com/chromium/tools/depot_tools/+/refs/heads/main/LICENSE
Source: same as homepage
Also, if accepted, please advise on what the name of the package should be (depot_tools or depot-tools or something else).