Will eIDAS be the only way to identify yourself in cases where it's needed, or will we be able to user other mechanisms like the german ID card stuff or an entirely separate alternative?

Or to put it another way, is a smartphone required? If not, that would already clear up a lot of issues, I think.

EDIT: Whoops, just saw the answer to another comment asking precisely this. So it's not a requirement. Good. Is there a legal framework that ensures that this remains the case? Otherwise, I fear it will become a de facto requirement over time.