If the features of Duolingo are available in another app (i.e. their various memorization techniques, vocabulary building, various interactive learning, etc.) that doesn't gamify or nag. Let me know since I really detest these aspects of Duolingo.

I succumbed to paying for the app since it is virtually unusable with the frequency of ads on the freemium model.

They are a very dislikable brand.

"one simple principle: make good products and charge money for them."

Thank you for the one-time purchase option. It's a win already on today's software world.

Does Costco even take Amex anymore?

Maybe they still do in Canada?

This is a super fun gizmo, it's discord channel is, uh, not great.

One cool thing is that you can talk to it serially. I pretty quickly had it organized with an IoT temperature sensor so that it could send commands to my ceiling fan given the temperature in my office.

I have also used it to capture the NFC code on a hotel card key so that I could still get into my room even after my key was inevitably "damaged" by nearness to other fields.

Some parts of it are silly, like the Tomagachi type game with the dolphin. Doesn't add value for me, but I can see how it might be something for someone.

There is also growing awareness with agencies about its flexibility, some apocryphal stories of them being confiscated by TSA checkpoints have come in.

Writing your own apps for them has a fairly high learning curve.