The 4A splitter won’t fry it. I’m using this exact one with my sensecaps. Think of it like a PC Power supply, your computer probably isn’t using all of that 1000w 80+ Titanium PSU, but it could.

https://www.amazon.com/dp/B07YB1JF2G/ref=cm_sw_r_awdo_navT_a_8PH60V39NW25E8PMQ7GM

There is also a Raspberry Pi4 in the product images. The same guts that are in your hotspot.

You also want a quality injector.

https://www.amazon.com/dp/B08LZZRX5N/ref=cm_sw_r_awdo_navT_a_G2WY7AJCXKGZ5Y7KZCX9

I used this one to provide the correct number of amps: https://www.amazon.com/gp/product/B07YB1JF2G/

Also the same Google WiFi bracket as yours.

I really wish Google WiFi supported PoE directly.