Best way to connect battery cells in parallel?

I would recommend you save your time and energy and use a professional battery system such as the PylonTech US2000 which already has a BMS and is configured to work directly with the Victron system using the common CANbus interface.

The PylonTech batteries also have a 10 year warranty and will save you a lot of hassle.

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom