Docker

I would use NFS instead of SMB. you will have all sorts of problems when you use smb, primarily permissions.

Also I wouldn't put all the data on the nas. What containers do you want to run? If you try to run something like nextcloud, you can just map your data directory to your nas. Databases, configfiles and so on aren't that big usually and your application will be a lot faster when those are on your local storage instead of the nas. For actually mapping your containers data to your nas you can just use bind mounts.

For the startup, you can set restart:never in your compose file and start the container with a script after bootup where you out something like 'sleep 120' in the beginning.

Make Docker depend on the mount. You can simply use systemctl edit docker.service and then

[Unit]
Requires=path-to-your-smb.mount
After=path-to-your-smb.mount

Then it will guarantee it's mounted by the time Docker starts.

Not personally used docker and SMB in that exact setup, but I would approach it as leaving the server to deal with SMB etc and docker to handle the volume after the fact.

But do you mean you have all your docker compose files on a different server connected via SMB, and from your host server running docker, so it needs to access the external SMB server?

I wouldn’t set it up like this. Config data itself should be negligible. Are you concerned with docker image data storage usage? Because your setup of having the configs elsewhere I believe wouldn’t solve the image size storage needs since the docker host would still pull them down