There are far too many variables to tell online.

Find someone that can come and take a look at your specific home and seek their advice.

I think what you are really asking is “how can I find out what other Internet providers offer service at my location”

And the answer is to go to this site and enter your address:

https://broadbandmap.fcc.gov/home

Using a switch will not make it slower. However, if the limits they impose are “per room” (or “per wall port”) then all the devices together will have to share that total speed.

If, however, you are very lucky and they impose the limit “per unique device” then each of the devices you connect to the switch will have its own allocation.

On amazon even normal switches have that term “splitter” in the description.

Even the TP-link switch that /u/1sh0t1b33r posted.

https://www.amazon.com/dp/B00A128S24

TP-Link TL-SG105, 5 Port Gigabit Unmanaged Ethernet Switch, Network Hub, Ethernet Splitter, Plug & Play, Fanless Metal Design

They include it because its a term many naive users search for.

That cable most likely does not meet specs for Ethernet.

That said, you could try to use it, and it might work (or it might not)

Use whichever pairs you like, but be sure you use the same set at each end of the connection, and that each pair corresponds with where an Ethernet pair should be.

This page has an image that shows which pairs go together:

https://doitforme.solutions/blog/ethernet-wiring-t568a-versus-t568b/