Cocomelon got us through a 3 hour flight and I'm not sorry, fight me
We'd been so strict about screen time before this, basically zero, proud of it even. Then came a 3 hour flight with a 20 month old who does not sit still, and Cocomelon on my phone with headphones bought us the only 90 minutes of peace on that entire trip. No regrets.
I know the general guidance is to avoid screens before 2 as a regular habit, and we still mostly do, this was a one-off for survival, not a new daily routine. The busy book and sticker pad I'd packed lasted about 12 minutes combined before being thrown at the seat in front. Sometimes the honest answer is a screen for a flight is a completely reasonable trade-off against everyone on the plane, including your own toddler, having a miserable time.
If it helps anyone else feeling guilty packing for a flight: download episodes beforehand since inflight wifi is unreliable, a cheap pair of kid headphones with volume limiting is worth carrying, and treating it as a "flight only" special thing rather than the everyday norm seemed to stop it from becoming a habit for us afterward. She hasn't asked for it at home since, it stayed a plane thing in her head.