Kits by LDO are a good starting point.
or
Note that V2 (currently V2.4) is not a successor to V1 (currently Trident). They are different printer designs. They also come in different sizes. More information can be found on their website.
There are multi material systems like the ERCF and toolhead changer like Tapchanger or Stealthchanger.
If you don't want to print the ABS parts for the printer yourself there is a program called Print It Forward where you get your parts printed in an existing Voron. There is also a ton of commercial vendors.
A Kind of mantra in the community is that you dont build a Voron but your Voron.
Do you have a source for Bambu using Marlin? It would mean they violated the GPL since their firmware is closed source afaik.