Friis transmission equation: how do I consider power loss along other directions?
The Friis equation considers transmission from a point source in free space emitting power spherically hence, the power emitted at a particular distance is in units of watts per square metre where the “square metre” part is that fraction of a sphere’s surface having a radius equivalent to the distance between transmitting antenna and receiving antenna.

Hence, all you need to know about the receiving antenna is its effective aperture (also described in square metres). The transmitting antenna is a simpler concept in the Friis equation.

Of course, the above is for an isotopic antenna which transmits power equally in all directions so, for a dipole or monopole, we know how much more power it can transmit or receive in its optimal direction and we add those dB to the Friis path loss equation to improve the path loss.

If there could be a receive antenna that totally surrounded a transmit antenna then the receive antenna would collect all the transmit power.

You need to google “effective aperture” and this tells you how much a receive antenna can collect when sat at the distance from the point source transmission. I think this might be the missing link in your learning.