确实不支持,但如果非要加的话,试着把这两行加到 sourcelist 中
deb http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu focal main
deb-src http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu focal main
https://launchpad.net/~nilarimogard/+archive/ubuntu/webupd8
当然后面也可以是其他的 Ubuntu 版本代号
deb http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu YOUR_UBUNTU_VERSION_HERE main
deb-src http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu YOUR_UBUNTU_VERSION_HERE main 

中文 
这个要怎么处理, 不支持吗?
sudo add-apt-repository ppa:nilarimogard/webupd8
[sudo] password for ussed:
Verification successful
Traceback (most recent call last):
File "/usr/bin/add-apt-repository", line 95, in
sp = SoftwareProperties(options=options)
File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 109, in __init__
self.reload_sourceslist()
File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 599, in reload_sourceslist
self.distro.get_sources(self.sourceslist)
File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 93, in get_sources
(self.id, self.codename))
aptsources.distro.NoDistroTemplateException: Error: could not find a distribution template for Deepin/n/a