Eh... yes. Probably. 5 years is development timeline for new platform. Like how VW MEB took from 2015 announcement to 2020 to be on the market.
However 3 years is more normal for individual model. Given its by 2028, I assume its mix of already in works model coming along earlier on and then new platform and model range in 2028. Hey Reading helps first 4 models by 26 and then next 4 by 28. So I would assume 4 old platform models now and they develop new platform to launch 4 models in 27-28. I would assume probably joint platform atleast partly with Toyota. Platforms are expensive to develop.
At one point, they did say they were too small to be able to develop the new platform, so would look for partners. Now we know it was Toyota, but Toyota was also late to the party