GPS is a great tool,
the vertical accuracy of GPS is several times the horizontal accuracy
trees and buildings can block the signal, or at least degrade the accuracy.
I use GPS primarily for control work when the error of the traverse closure would probably exceed the accuracy of the GPS.
I have used GPS to do topography of dirt and other times that survey grade accuracy was not required for the data being collected
my typical GPS project involves using the GPS for the control traverse, it is very easy to locate the monuments in an entire section and set your control to due the site survey with the instrument
survey grade GPS is differential GPS, in other words it requires two GPS receivers. One is configured as a base station and transmits a correction to the rover, the base can also be a network base but you need an internet connection for that, the second receiver is the river that you use to collect the data
How big are your diy projects?
the reason I ask this is my old robotic instruments are capable of survey grade accuracy out to 1200’ with a mini prism.