Is there a way to use !includes in UI configurable dashboards?
No, it’s not possible. If you want more info on why, its in the discussion here:
Nothing is impossible. It just require additional work or conceprual changes etc.
It’s the same issue like comments in gui maintained automations. The fact that parsers don’t recognize comments as lexical elements (instead they remove comments in the first step of processing) doesn’t mean it cannot be changed or achieved different way.
BTW it’s another argument against converting yaml to json hy using generic parsers. but the dice have bern thrown…
If you know of a way to do this today in the current product please share. I’m not aware of one but I’d be happy to be wrong.
If you’re saying the product could change to accommodate this, sure. I already directed the author to the feature request they can upvote. Doesn’t help them today though.
There might be several ways, from writing/modifying parser in order to accept non-tree-structured yaml elements as language tokens up to storing yaml “as is” and parse it at the moment of execution.
Devs never shared real motivation behind their decission (I can imagine it though) so I’m not going to guess. Just saying that what has been programmed may be re-programmed.
My man, he’s asking you if there’s a way to do it without code changes. He also knows the answer: It’s not possible.
Also, just so you know, he’s on the dev team 
as in, one of the paid guys
ok, right. no, it’s not possible without code changes.
I was reacting on linked reasoning.
To preserve comments one solution could be to use JSON5 instead of standard JSON for lovelace cards and automations? json5 · PyPI