Overseas multi-country trip with baby and toddler - two travel strollers or one double stroller?

We are planning a multi-country trip overseas to visit family and do some sightseeing. We will have a 6 month old and 3 year old. Our 3 YO is very accustomed to his stroller and to be honest, gets into trouble when he’s not in the stroller as he likes to zig zag down pathways, pick up everything including litter and spontaneously run away. We’ll be out all day too so he’ll definitely get tired and need to be sitting in a stroller for breaks.

We are debating if we should bring 2 foldable travel strollers (such as the uppababy minu), or just bring one full size stroller that can fit both kids (uppababy vista).

The travel strollers are great because they fold up so small that they can fit inside cars more easily (potentially in the floor of the backseat, leaving the trunk available for luggage). They can easily navigate the small walkways we are bound to encounter and tiny restaurants. We could also potentially fit them in the overhead bins of the plane rather than risk them getting broken from gate check.

That said the downside is both hubby and I would have to push them, and if we encounter stairs, we’d have to leave one stroller at one end while we lift the other stroller and then leave the other stroller while we move the second stroller.

We could solve this by having just the one big stroller, but it’s going to be cumbersome when we are on cars with all our luggage, on crammed subways, or if we want to take a cable car somewhere, etc. We will also have to gate check it and I’ve heard horror stories of uppababy vistas being broken when they are gate checked.

What would you suggest?