StarTech makes a USB-to-KVM that looked promising to me, but it's still >$400: https://www.startech.com/Server-Management/KVM-Switches/Port...
A more extreme example was when I went down the rabbit hole of trying to set up remotely unlocked full disk encryption on a cloud, just to see what was possible. This was maybe 4-5 years ago. This involved a pre-boot environment that would run from memory only, packaged into an initramfs and used dropbear as an ssh server to accept a connection.
I really, really wish cloud VMs had virtual KVMs. It turns out, it's really easy to mess this up, and when you do recovery is Non Trivial.
The best I found was that Azure's cloud allows you to connect (read/write!) a virtual serial port via web interface so you can use the Linux serial console to recover. That was a game changer for playing with this. If dropbear failed to come up, I at least got a shell into the pre-boot environment.
One thing I've ran into was root not having a password since the cloud images are typically SSH key auth only. That was annoying when trying to fix something simple like iptables or entering maintenance mode for a disk check.