Not sure why someone would. Bitwarden provides their own self-host repos and docs and is working on a unified container instead of docker-compose scripts for their production stack.
I've been using their stack for the last 6 years and only issues I've ran into were my fault. Also tested their container and will be switching to that soon.
Battery is definitely a longevity concern on iPhones. Most people I know with iPhones are tethered to a charger when traveling or camping and other heavy use days.
That's funny to hear as daily for work I use k3s and RKE2 for deployments and testing and at home I use unraid specifically because of all the k3s work I do even k3s has too much overhead for updates and backups and all that IMO.
https://bitwarden.com/help/install-on-premise-linux/
https://bitwarden.com/blog/new-deployment-option-for-self-hosting-bitwarden/
If you want the non forked stack that gets regular security tests published.