I would start here, master source players both playing the tunes on the pipes and singing them
https://www.musicinscotland.com/acatalog/Masters_Of_Piobaireachd.html
Yes in Highland pipe pedagogy there are tunes considered beginner tunes, but I don’t know if I would worry too much about that. I would start with one that has an Urlar you really like. Some pibrochs have lovely attractive melodic Urlars, some sound almost random.
I was started on Lament For The Old Sword.
My current favourite to play is Lament For Captain MacDougall which has a lovely urlar and some nice tuneful variations.
As you listen to ceol mor you’ll note that there are various modes used and these of course give different feels.
Some have a straight A Major feel, loads of lovely Major 3rds, tuneful, pretty, and harmonious.
https://www.youtube.com/watch?v=ZH78VQ-v4AQ&t=25s
There are many in various gap scales, pentatonic scales, such as the common Highland pipe A pentatonic scale A B D E G, which gives an archaic haunting sound.
A very nice tune in that mode is Lament For MacSwan Of Roaig.
https://www.youtube.com/watch?v=IHmStEFguik
There are a few pibrochs which have the feel of being in B minor for example Salute On The Birth Of Rory Mor MacLeod.
https://www.youtube.com/watch?v=zUubpVzRso0
There are tunes in the key of G, which have an odd sound over the A drones. Lacking the note C, tunes like The Earl Of Seaforth’s Salute can be thought of as being in G Major.
Introduce the note C, which is C# on the pipes, and tunes in the key of G are in the Lydian mode. This is possibly the oddest-sounding mode of the pipes. An example is Lady Margaret MacDonald’s Salute.
https://www.youtube.com/watch?v=rbBJQRoVgHY&t=56s
The Highland piping world is heavily involved with sheet music and a vast number of pibrochs are in print.
For the serious students there’s the Piobaireachd Society, the main authority/source
http://www.piobaireachd.co.uk/
A very handy collection is the Kilberry Book, which was our text-book at piping school.
https://www.thepipershut.com/product-p/kilberry.htm
But really I don’t know if you need to get the sheet music. For many generations pipers learned by ear, and the only way pibrochs were notated was in canntaireachd. We have many pibrochs that only survive in canntaireachd. BTW the timing of the notes in written ceol mor doesn’t usually capture the way the tunes are played.