I use a variety of LED strips and strings around the house, but unfortunately for this discussion no Lifx strips. I did glance at the Lifx web page. The interesting feature of the Lifx strips is the addressable sections of each strip. That feature makes me wonder will the strips work with splitters and extension cables as you mentioned you may need?
It’s the darn transformers and controllers that complicate the use of LED strips and their integration with SmartThings. Most basic strips have a small transformer, a controller and the controller uses Wi-Fi or Bluetooth to communicate with that manufacturer’s phone/tablet application and SmartThings via a controlled outlet turns off or on the strip. With the basic strips, splitters and extension cables work fine. You’ll need to contact Lifx to see if or how splitters and extension cables work or fine a Lifx discussion group. Intermediate level strips involve zwave or zig bee controllers (Fibaro, Dresden, etc) controlled directly by SmartThings using Smart Lighting Automation control or WebCORE. Intermediate strip configurations might involve buying 5 meter length strips and making smaller strips using solder or mechanical connectors. Advanced strips might include addressable strips or strings and micro computer control. Basic, intermediate and advanced are my definitions not a recognized standard.
I use a variety of power supplies and controllers placed all over the house, garage and outdoors. My first purchase was a Hue strip used as an above kitchen cabinets accent lighting. Followed that with a couple Osram strips for under cabinet lighting. The Osram has a variety of splitters and extensions. Even have Osram outdoors on the deck. In the garage, I have single color (white) double row strips powered by a transformer without a controller and it’s plugged into an Iris plugin outlet. I have a variety of power supplies and controllers and strips, mostly purchased from Amazon. The power supplies and strips are “name brand” LEDenet, Chinly, Alitove, and etc. Controllers are Dresden, Fibaro, Qubino and some generic Wi-Fi and Bluetooth controllers. One way or another SmartThings or Alexa has control over my LED strips, except two cheap strips behind TVs plugged into the TVs’ USB ports.
Although expensive, the Lifx or Hue are indeed very convenient, easily controlled and produce lovely white and colorful lights.