Your standalone Proxmox VE node comes with a number of services running by default. Having in mind the target system's particularities assumed in this guide series, there's some reconfiguring or ...
Check with pvs its current state. $ sudo pvs PV VG Fmt Attr PSize PFree /dev/sda5 debiandemo-vg lvm2 a-- <4.52g 0 Notice that its PSize is only around 4.5 GiB. Use pvresize to expand the sda5 PV. $ ...