The Cruz is definitely what you are looking for - as a bucket seat (more about those in this article here), it is slanted and best from 5-6 months up. There definitely are inserts that make the seat later, but also smaller, so it is not the best option if your baby is long and chubby.
You need a true lie-flat seat, e.g. such as a Joie Versatrax / Joie Finiti / Joie Aeria / Valco Ultra Trend has. However, if it is a reversible one, it will always be smaller (read more about reversible seat units here). One of the larger reversible seats are definitely on the Kinderkraft Everyday or the Baby Jogger City Premier. but those are definitely not lightweight.
What I would get in your situation is, therefore a non-reversible, forward-facing only pushchair that will be lighter while more spacious and also more compact and affordable. My roomy suggestions would be a Valco Trend (not Ultra, those are reversible), Oyster Zero (super wide seat and great canopy), Britax B-Motion 4 Plus (on the heavier side but a long seat for sure) or the Baby Jogger City Mini2. There, in the fully reclined position (and if needed, a cocoon for the baby) can be used with a 3mo facing the street, and will be spacious enough to last you longer than a reversible one.
P.S. Your baby can be a bit cramped in the carrycot, so if his legs are not already out, wait at least a few months more - babies were super squeezed in the belly, too, and it makes them feel safe, so don't think a bit tighter space of the carrycot needs to be changed immediately ;-)