Bugaboo butterfly, joolz aer, yoyo, cybex orfeo you can get car seat adaptors for any of them if it’s an infant carrier car seat you mean?
The Doona is super convenient for this, although I believe it doesn’t score as high for safety ratings as some other infant car seats. It’s also not recommended to have your baby in a car seat for long periods of time, so if they are likely to be in the pushchair a lot, I would take both personally.
Depends what you're doing and where you're going. I took my little one to corfu and didn't bother taking a car seat at all