This achievement description is a little misleading. You must unlock everything AND upgrade all of the items that have upgrades. There are more tech points on the map than what you'll need to do this.
You will need the following achievement condition to be completed, as it is required to complete this achievement, and doing it first enables the easiest method of finishing this achievement:
(If you already have that achievement but have since started a new game, simply turn all areas defiant again, the achievement itself isn't what's needed, it's what you get from doing it's tasks that are.)
Earning this achievement as soon as possible will reveal all remaining tech points on your map, no more need for a web-based one! It also comes with 2 skills that contribute to this achievement, and are very helpful later in the game.
To collect tech points the easy way, invest in a Infiltrator Spiderbot and find a construction worker to play as.
otherwise construction workers are easily found in restricted areas with access for construction uniforms, such as the one directly north of the Horseferry road fast travel point in Westminster. Using the construction drone and the Spiderbot, you can get i'd say about 90% of the tech points with no additional tools. The remaining 10% are locked behind puzzles.
Some points may be hidden behind wooden walls. You can shoot these, even with the shock weapons. I suggest getting the silent shock pistol as soon as you can for this sole purpose.
Some points may also be hidden under props and scissor lifts. Move these out of the way how you see fit. The Spiderbot normally works
If you find yourself stuck on a tech point, skip it and find a different one, there are plenty to go around.
This achievement will pop after you apply the last upgrade or acquire the last skill. You can create a simultaneous pop with Take back London (shown above) or
If the achievement does not pop. Double check you have all the upgrades. Quit to the main menu, restart the game, and it should pop when you load back in. If it doesn't wait a day and try again. It's server-side, so make sure you're connected to the internet.