If you are on a strict routine which involves naps in cots in the dark and you have followed this since an early age, babies/toddlers often will never sleep in a pushchair.
Mine were on the strict routine and slept in cots. Fantastic sleepers, both in the daytime and at night too, but we did live quite restricted lives until the naps stopped as they turned 3.
If I was going to a friends I would take travel cot and they woulD sleep there just as well as at home,if in a dark, quiet room.
The thing to remember is that the naps reduce as they get older. By the age of 2 ish the nap needed to be down to less than an hour to ensure they where tired by bedtime. So yes, you might be restricted for a while longer, but the morning and or afternoon should get a bit longer. Some children drop the after lunch nap by 2 although often the great sleepers keep going with it until almost 3.
I found that once mine got to about 27 months, they could cope with an odd day or no nap at all, as long as it was very occasional.
Can see it is tricky if you have 2, but suspect you don't, because few people with 2 manage the strict in their bed for all naps routine as rigidly and the children do learn to sleep in the buggy from necessity early on.
IMO, the bit of inflexibility is worth it for the great night time and day time sleep. The majority of the time you don't need to be out the whole time.