OP here, thanks all! You have convinced me keep her in the P&P for now. She is napping right now in it We got a video monitor so the grandparents don't stress too much about her climbing out (which she has only tried half-heartedly at home so far).

Great question!

We have the baby bjorn travel crib which worked well for our very tall DD.

I have my two year old sleep in a pack and play during travel also. You’re already going to have your kid trying to nap and sleep in an unfamiliar place, if she’s used to being in a crib, you’re probably gonna have better luck getting her to relax and sleep in a environment close to that, which would be a pack and play, vs a cot where she is not “contained.” I’d hold off on the travel car until she sleeping in a bed at home so her sleeping environment isn’t changing so drastically. Kids fold and bend easily in a pack and play!

We kept my twins in the pack & play well beyond when they reasonably fit because we needed the containment. (It was infrequent, and they didn't seem bothered.)

After the P&Ps, we moved to the Regalo travel cots, which we still use now that they're 5.

Try the hiccapop air mattress bed. (Check Amazon). It’s compact, light, easy to store and transport. Good luck!

Our 2 yo is 36 inches so we're realizing she's too tall for the pack and play. She still sleeps in the crib at home. We need something for her to sleep in (a) when we travel and (b) to keep at her grandparents' house. Recommendations appreciated as well as advice given we're used to being able to contain her, so how do you keep them safe if alone in a room while traveling?