Its been awhile since I’ve run Nextcloud but when I did on a pi the interface was slow and the instance itself was unreliable.

Currently my NAS runs TrueNAS and pretty much just serves files. I guess I could run a Nextcloud container on TrueNAS, but I’m thinking I may get better performance with it running on a more robust machine.

Yea proxmox on one machine and a separate machine running truenas and serving NFS

I believe you can host your data if you prefer