How to have device-specific values in .dir-locals.el

I use [[Emacs]] on my laptop and on my phone (in [[Termux]]), and I use [[org-roam]] on both devices.

I have two org-roam-based projects. One is this public digital garden, one is a private space. Because I have two projects, I have to use the .dir-locals.el file to set the location of org-roam-directory and org-roam-db-location per project.

The locations of the org-roam directories and their DBs are different on my laptop and my phone. So, I need a way to have device-specific values in .dir-locals.el.

I have one .dir-locals.el synced between the devices with [[syncthing]]. It sets values other than just these ones.

I was doing this fairly naively for a while, having a line for each and commenting it out each time I was working on a different device:

((nil
  (org-mode ngm-journal-mode))
 (org-mode
  ;(org-roam-directory . "/home/neil/org/Personal/")
  (org-roam-directory . "~/storage/shared/org/Personal/")
  ;(org-roam-db-location . "/home/neil/org/Personal/org-roam.db")))
  (org-roam-db-location . "~/storage/shared/org/Personal/org-roam.db")))

But that got a bit annoying.

Now I've got a conditional checking for the hostname and setting the variables accordingly:

((nil
  (org-mode ngm-journal-mode))
 (org-mode
  (eval . (cond
	   ;; Laptop configuration
	   ((string= system-name "neil-ThinkPad-T450s")
	    (setq-local org-roam-directory "/home/neil/org/Personal/")
	    (setq-local org-roam-db-location "/home/neil/org/Personal/org-roam.db"))
	   ;; Phone configuration
	   ((string= system-name "localhost")
	    (setq-local org-roam-directory "~/storage/shared/org/Personal/")
	    (setq-local org-roam-db-location "~/storage/shared/org/Personal/org-roam.db"))))))

That's working, although I'm not totally happy with it. Seems a bit crufty - the duplication doesn't feel great.

When I get chance, I'll investigate making use of .dir-locals-2.el.

You can also use .dir-locals-2.el; if found in the same directory as .dir-locals.el, Emacs loads it in addition to .dir-locals.el. This is useful when .dir-locals.el is under version control in a shared repository and can’t be used for personal customizations.

– Directory Variables (GNU Emacs Manual)

I should also double-check whether I could just use relative paths, which would solve this specific problem.