As a professional MD/accompanist and avocational "score hound" I've seen that in the past 20 years or so, there's been a fundamental shift away from the Piano-Vocal selections being "arranged" (back in the Golden Age) to the published vocal selections being almost unilaterally taken from the Piano-Vocal scores used by shows during their professional run, right down to all the harmony assignments. (For a while, there were even "Piano-Vocal" editions, with "just" an accompaniment, and "Piano-Vocal-Melody In the Right Hand" editions for people who wanted to play the song without singing.)
I've also changed my views on "what students should be singing to". Back when you could purchase an actual score to a musical (again, the Golden Age repertoire) singing/playing from the score was preferable. But trying to work from unpublished scores was a chore, as they were often Piano-Conductor scores with multiple cues and too many notes for ten fingers; accompanists learned to just "do our best" with it. Even now, the new Piano-Vocal books aren't always optimally playable (just ask anyone who's tried to play "The Beauty Is" from the Piazza P-V book with the melody interpolated.) :)
The best resource now is the Singers Musical Theatre Anthology, which presents the actual original score versions and keys of songs in a readable published format.
As for Come From Away, I can tell you, having purchased it, that the published vocal selection is as authentic as you're going to get in a piano-vocal book. To get any more authentic, you need a full orchestration. :)
You can buy the vocal selections for about $23: https://www.amazon.com/dp/0571529976/
Everything that can be bought, should be bought. Encourage the artists you like. This sub is (or should ideally only be) for "rental only" items that cannot be legally bought.
$12.80 for the Kindle version, $18 for the paperback:
https://www.amazon.com/dp/B06XVX2X6M/
You like the composers' work? Purchase it whenever possible so they continue writing.
(If you live in a region of the world with another Amazon extension simply substitute the .com for your local extension.)
Yes, the vocal arrangements are included. There's a Kindle edition (at least here in the US - not sure about Amazon sellers in Europe) and you can see the arrangements in the Kindle preview. :)