Combine multiple 4G LTE connections

Are there any solutions to combine multiple 4G LTE services?

For example if I were to use multiple Spitz GL-X750 and have them connect to another device to combine the 4G connections.
Or maybe there is another device I can insert multiple sim cards into then connect that device to my router?

Hi Feraily,
According to your requirements, I recommend X1200. GL-X1200 / Amarok - GL.iNet