Missing best practices in the docs, in regarding to the tables primary key types

I think that it will be good to add documentation for best practices for choosing the correct primary keys types.
To be more specific if one should use uuid or bigint for the tables.

I've asked a question in stackoverflow about it, since I didn't find a strict answer about it: https://stackoverflow.com/questions/70505619/primary-keys-uuid-sequence-strategy-on-citus

As explained in the stackoverflow example:

User
UserId uuid/bigint?

Device
Device Id uuid/bigint?
UserId (here for the distribution key)

In the above example, we want to distribute the user data according to the UserId, for example his Devices. What should be the primary key ids types? If UUID is the answer, should we be afraid of fragmentations in the nodes?