@dalias OK, after digging around a bit to verify that things are properly uninterruptible and support passthrough, I found https://voltaicsystems.com/v88/
A bit big and not cheap, but it looks like it meets all your requirements. They have smaller/cheaper ones but that don't support USB-C PD or not up to 20V.
GNU social JP is a social network, courtesy of GNU social JP管理人. It runs on GNU social, version 2.0.2-dev, available under the GNU Affero General Public License.
All GNU social JP content and data are available under the Creative Commons Attribution 3.0 license.