I don't think NixOS meets the bill. You'd be learning and troubleshooting a whole new language just to setup your system and modify the core configuration.
Admittedly I've only used it with a preconfigured theme and no need for real customization. If you do need those features, I'd imagine the other commenters are correct.
I would also recommend Hugo, and believe it meets your requirements. The header markdown looks very similar to what you wrote, and it has tags. I'm not sure about a tag "cloud" the way you imagine it, but it's worth looking into.
Neither of these are IDEs (nor is VSCode), but it'd be Zed and Neovim for me. Zed is fast and pleasant to use, but also will enshittify eventually. Debug support is in progress but not live. Neovim is fun and it's nice to be more in control of what is going on, but I haven't made the necessary progress to be productive in large projects with it yet. I was excited for Lapce but it fell short, had too many issues in a short time.
I think btrfs ticks all your boxes. I would suggest yabsnap for snapshots. Then if you want a backup off-disk use borg or btrfs has a way to transmit (sync) to a remote. Yabsnap has a command which will make a script to restore from backup, which you can review and run.
I have a Canon MX340 (maybe pixma?) that works with gutenprint. The ADF is a bit messed up but it otherwise works as intended. If you have a similar model, it will probably be supported.
I have DS4 working in Arch with Wine. As someone else mentioned, the hid-playstation kmod just worked out of the box. The key for some games to work properly was to add a SDL2 gamepad mapping.
I have a storage VPS and use Borg backup with Borgmatic. In my case, I have multiple systems in different repos on the remote. There are several providers, such as hetzner, borgbase, and rsync.net that offer borg storage, in the event you don't want to manage the server yourself.
It's increasingly harder to exchange for fiat anonymously, especially when you consider XMR or other privacy coins. Once the people in charge of money realized they were a bit subverted, you got the huge crackdown.
I still use it for various things. Buy LTC from a legit licensed exchange. Move it around a bit. Change to XMR through an exchange that doesn't care. Maybe move it around some more. It's a giant pain, but I don't know a better way. This method isn't perfect, more of a balance of risk, but it's better than just handing your entire entity over for a simple transaction.
Maybe one of the Fedora Atomic distros would be up your alley? https://fedoraproject.org/atomic-desktops/
I don't think NixOS meets the bill. You'd be learning and troubleshooting a whole new language just to setup your system and modify the core configuration.