PSA may have brought some expertise regarding design for lower procurement costs, but in terms of technical solutions, the group has no experience of designing large RWD vehicles.
The BEV project now called STLA Large was one of two offshoots of Giorgio. The first, Giorgio Global, has already produced WL Grand Cherokee, and is capable of producing ICE, Hybrid or BEV models, but is optimised for ICE; the second project is longer-term, to design a “BEV matrix architecture” that could produce a family of vehicles without the restrictions imposed by the need for an ICE power train. Maserati is also involved in this BEV project, as it will underpin electric cars from Maserati and (recently confirmed) future Alfa models, but the lead group is in Auburn Hills..
Development of the BEV architecture started at least two years ago, possibly three. 2024 seems credible as a model intro.
But... Charger is more likely to be a Giorgio Global car than a STLA Large one. I saw a document from 2019 where it was listed as a Giorgio Global product, beside WL and the next Maserati QP. It may have been delayed or changed a couple of times, but it was definitely planned at that point.
(I’m using STLA Large to refer to the BEV-only cars and Giorgio Global to refer to ones that will have ICE; that’s only my shorthand, I have no idea how they’re called within Stellantis)