-you can try tinkering around with gentoo in a virtual machine
-you can try setting up ESXi or Proxmox as a hypervisor and set up some VMs in there
-you can try setting up pfsense, vyos, or openwrt as a router if you want to try some networking stuff
-you can try setting up a server VM in something like debian, ubuntu, or almalinux to try to set up a DNS server or DHCP or web server or fastapi server or something
-you can try playing around with docker containers