My son is almost 1 and is very strong. We love this playpen bc of the size, easy set up and storage. Very durable Sweeby Baby Playpen, 59x59 Inch... https://www.amazon.com/dp/B0CSFZ9KKT?ref=ppx_pop_mob_ap_share
I still use a travel cot as a playpen for my 15 month twins in the house. I have one by hauk and it’s very sturdy. They both pull themselves up and lean on it and it’s fine. My mum also has one at her house. Folds away small . Thibk it’s called hauk dream and play
https://amzn.eu/d/fhexsfL We have this one, depending on size of your grandparents place there’s two different sizes. 120x120cm and 150x150cm.