The saw you hope for does exist Alex. The mafell kss 40. Lightweight, circular saw, crosscut saw, track saw, all in one. The mafell tracks are the EXACT same as bosch tracks other than color, buy the bosch for a fraction of the price. Mafell is also on the cordless alliance battery system so metabo batteries (who make the mafell batteries) work in it for a fraction of the cost.
It's pricey. The weakness of mafell is that Timberwolf tools controls 100% of the sales in the US and they appear to also be the ones in control of expanding sales to other stores. As such, the kit costs $1315 which includes saw, crosscut track, flexi track, systainer, two batteries. For your needs, this would cover everything. Having a rollup track might be intriguing to you for simply doing plywood cuts.
The only weakness I see in this saw is that it has a small blade and wont cut a 2x4 when on the track. Depending on the type of work you do, this might not matter.
As far as the milwaukee goes: It's good to see them continue to grow and I have unlimited milwaukee batteries. I already have the mafell cordless tracksaw so I wont be seeing red soon.
Truly, the saws I want to see more of are the crosscut saws. Mafell is essentially the only company with an assortment of them. Festool has at least one with a corded and cordless option, but is rumored to be underpowered. Metabo makes some that are compatible with crosscut tracks, but the track and saw don't play together well. I like my mafell enough that it eliminated a 4" 6-1/2" and 7-1/4" circular saw from my truck. I use it to make general cuts, light framing work, trim work, scribing, flooring, and basic tracksaw duties. If I could get a 6-1/2" lightweight milwaukee crosscut saw... that would be a dream.