Networking – improved bandwidth at home by connecting or merging mobile data and home internet (via an Utp cable)

Work from home with children and soon a spouse. So I'm thinking of increasing my internet performance. I have broadband, nominally 100/40 bit / s, but struggle with higher loads.
And I have a pretty decent 4G bandwidth.
Ubuntu 04/18/4

With an excellent tutorial here I was able to connect my home Ethernet and my mobile hotspot.
Well i think i was. Once I got it up and running, I ran a speed test and noticed no difference.

The default configuration in the tutorial is "failover". It is therefore not surprising that no bandwidth improvement has been achieved.

I quickly realized that there are a lot that I don't know.

1] Is it possible to connect two such interfaces that are each connected to different networks? I think it should be.

2] There are load balancing modes: round robin and two adaptive modes. In practice, do these actually have advantages for a single user on a laptop?

I tried to use one of the adaptive load sharing modes, but I didn't see any improvement in the speed test either.

3] There is something more modern called "teaming", but I could not understand whether it is equivalent for my purpose