I've got lenovo YOGA s730 with Ubuntu 20.04 and can't turn on fingerprint login. In other questions on forum people have troubles with turning on fingerprint in settings > users > authentication and login, but I don't even have a button there, which is strange, since there should be built-in feature in 20.04, right?
The Yoga 730 uses a "special" Synaptics fingerprint reader that does not work out of the box with either
thinkfinger. There is a prototype driver being built by some talented people, but it's not 100% solid just yet.
For the moment the fingerprint reader on your Lenovo will likely sit idle. Hopefully there will be a compatible driver available by the time the next LTS rolls around.