I dont really care if they are really accurate until they give you an idea of where you heading.
How on earth you will be able to start a planted aquarium without a general knowledge of the water you will used to fill it.
And the same knowledge about the water you used at water change.
and the accumulation and the disparition of the element used by plants.
I care about magnesium and ca and fe and so, because they are essential to plants and fish and people life.
... and if your are color blind, find afriend to help you with this.
Without these basics informations it will be really hard to have any success and any control. You can look how long you want to your plants you will not be able to manage a complex microsystem with animals and plants, only by luck it will work but I assured you, not for long.
Now let’s be serious...
Step one: Have a good knowledge of the type of tank you want (planted, african lake or other)
Step 2: find some place where you can have acces to water that approach closely at possible the type of water from the habitat choose in step one
Step 3: add ro water or add nutrients to that water to match what you need
Remark: remember that evaporation water is pure, meaning without nutrient and most fish tank have tendancy to have some accumulation of nutrient and over time nutrients can become unbalance with the uptake of different elements
Step 4: with good condition and water changes (step 2 and 3)
you will probably enjoy the hobby without to much of the testing part.