Can't chime in for Netherlands, but here in Denmark you can get an actual code card you use for 2FA. It has 100 codes on it.

If you're doing online shopping/purchases chances are you have a phone though.

My guess is they will send a code to your registered address, which is a must if you live in the Netherlands. I just lost my phone and retrieved my DigiID through this way.

To set up digid, you apply via official website (or app), receive one-time code in your paper mail, then proceed back to the same website/app to register your password and phone number. App registers itself if you're using one.

Once set up, you have 3 authentication methods, selectable on login page:

1) password only (low-trust authentication, not all places accept this, certainly not your doctor's office);

2) password + 2nd factor via SMS/text (high-trust);

3) password + 2nd factor via app (high-trust).

Bicycle down to the local Gemeente office and talk to someone?

I think it's possible to "assign" someone and grant permission for them to access information, a bit like power of attorney.