Product Backlog

Scrum Guide describes the required attributes. One is free to add any other attributes.

Would a "grouping" attribute in the Product Backlog provide greater visibility and transparency into potential work, considering that multiple Scrum Teams are working from that Product Backlog?

When multiple teams are working on the same product, they will need to visualize and manage their dependencies. Using further attributes to qualify Product Backlog items may then be advantageous.

'A Product Backlog attribute that groups items may then be employed'

Another thought - a complimentary practice may be to leverage an Epic or Feature attribute.  If you have feature teams, organizing work this way may eliminate/reduce dependencies between teams.

Is there a property that can be used to distinguish the domains where individual teams have their strenghts? An attribute can then be introduced that gives a hint to what domain the Backlog Item belongs, thus giving a hint what teams best work on that Item.

As mentioned one is free to add aditional attributes. At least some form of state is also needed to distinguish "ready" items. The "epic" state Chris proposes could also be seen a state. The question would be if it is worth for the team to destingish "non ready items" from "non ready epic items". Both have to be further refined until "ready". Being ready they cannot be epic anymore. I can imagine (unnecessary?) discussions if so and so item is an epic or not.

Thank all that helps !