Allow multiple nix stores in nix-daemon?

I sometimes need to run nix builds that require a bunch of storage or a different set of cached paths than what I like to carry around in my primary system nix store. For that purpose, I’ve usually used NIX_REMOTE=... to use the other location.

That however has the downside that it runs builds without a sandbox as my user which I don’t want.

Is there a way to have another nix-daemon that runs the same config as the primary one but uses some other path as its base? Or make the primary nix-daemon able to use trust multiple paths as its Nix store?

Note that I don’t want a different store prefix for derivation purposes; that should remain /nix/store/! Only --store/NIX_REMOTE should change.

Maybe something with a local-overlay-store?
https://nix.dev/manual/nix/2.22/store/types/experimental-local-overlay-store

I’m not quite sure how that’d help.

I can create and use a secondary plain directory nix store just fine; it’s using it with a daemon that’s the issue.