I updated OpenBSD to 6.8 and Ubuntu to 20.10 on the cli over ssh. OpenBSD does it better with sysupgrade. Both machines have a similar setup. With OpenBSD I ran sysupgrade and had to do nothing during the upgrade. After that follow two advices and two package updates. With Ubuntu I had to look several times at the console because the process just waited for me to do some input. This was annoying. And upgrading OpenBSD was far faster than upgrading Ubuntu. But both went fine. Nothing in comparison the non-existing upgrade path from CentOS 7 to CentOS 8 where I tried it and just hosed my machine.