I was unable to reproduce this on a Lubuntu 19.04 host machine using the 4.19.0-13-generic kernel and qemu-kvm 1:3.1+dfsg-2ubuntu1. My keyboard worked in both the live system and the installed vm. I also tested Oracle VirtualBox 6.0.4-dfsg-5 and had no issue there as well.
I was unable to reproduce this on a Lubuntu 19.04 host machine using the 4.19.0-13-generic kernel and qemu-kvm 1:3.1+dfsg- 2ubuntu1. My keyboard worked in both the live system and the installed vm. I also tested Oracle VirtualBox 6.0.4-dfsg-5 and had no issue there as well.