Wordpress (I'm evaulating this for a suitable Joplin replacement ) In short - I found that it's easier to reference a site instead of installing Joplin when I rebuild my computer.
Psono password manager
You may wonder why I am using Zitadel and Authentik, I first started with Zitadel, and moved to Authentik, but am evaluating both. They both have their positives. So far Authentik has been the most useful for me. And about the two password managers, I use Vaultwarden as it supports everything I need including Passkey support. My step daughter who is an adult is disabled so having an easier password like Psono makes it easier for her.
Can't speak for OP but I can say that I switched to proxmox from just running docker and services native. Proxmox offers a lot of flexibility, you can do snapshots, build many different LXC containers very easily, to keep things separate or have better control over resource usage. Also I run mine in a 3 node cluster so I can do live migration of VMs and pretty quick migrations of LXC containers. This all allows me to run my services with little to no downtime and have redundancy.
Because, for Home Assistant, I moved it from Raspberry Pi 4 to a KVM and found it faster. I use Proxmox for that which I found to play nicer with it than just setting up a Debian Server and spinning up a KVM via QEMU on a desktop. I've been there and had issues over time. As for why LXC's they are smaller and the only ones I use are from https://tteck.github.io/Proxmox/ which makes them super simple to set up and run!