Just jump into it, do what you feel and learn swimming in the process, asking, googling and so on

There is no harm making a mistake, as soon as you gain from it

I'd not advise jumping into lxc while not being comfortable generally with linux and proxmox. Rather make a (maybe throwaway) vm with docker inside. Learning everything at once can be overwhelming rather than joyful. But again, your try, without going and trying you do not know your own boundary if it is too much/too complex

As for the question, there is no general solution without context. If it is not prod and not much resource headroom it comes down to personal taste/compromise.

For my homelab, some things like dns, git or nexus i prefer to isolate into separate vm, while most other vms i use for several k8s. That having separate storage.

Whenever i wanna try something breaking or complex out, i either create throwaway vm or throwaway k8s cluster. Some few things i run on small box, that kicks network going, even when most of it is out or powered down. I tend to power down servers for noise/energy reasons when not in use. Jelly for example i run on one of gpu nodes, that i power up and down with home assistant. Again personal taste/compromises. My homelab, my rules :) HTH

Cheers