If so, this means that still anyone could pull X*N sats in total. Like this the implementation doesn't seem to be usable in the real world yet. There would have to be some security mechanism in place to make a payment link non-reusable.

Even entering some sort of PIN doesn't seem to be a fitting solution as this PIN — once entered into a POS terminal — could then be used with the respective LNURL-withdraw link to pull funds as one pleases.

If someone more knowledgeable could clear up any mistakes I made in my reasoning, I'd really appreciate it.

Any ideas yet on how to overcome these issues?

This is a really cool idea and an awesome new project to try out.

The BIG downside I see with this is that whoever can read the contents of the NFC chip, has access to the LNURL-withdraw link and can thus drain the entire node's funds.

Am I seeing this correctly or am I missing something?

This is not a contradiction.

What they are showing is that Lightning enables proprietary services to communicate and transact with each other, even if they use a different currency (e.g. dollars and reais).

To reach such an integration you have to work with the respective companies/exchanges to get them to build on top of lightning.

However due to lightning being an open standard anyone can send money to someone on Bipa (Brazilian exchange) by sending sats to the according lightning address. So sending money to someone who is using the Bipa App is not limited to ZEBEDEE users but open to everyone using the lightning network.

The only perk for ZEBEDEE users who have an Bipa account is an easier and linked UI.