Not for the faint of heart
Lots of good, fun ideas here. But beware that the descriptions you see on this & similar sites may be more complex than the poster describes.
I have a 2017 TSI Wolfsburg. All my new cars get a larger rear sway bar (this one got 22 mm upgraded GTI bar), tint, & the best tires money can buy for the frequently wet Seattle area roads. Those things are easy, can be done by practically anyone at reasonable costs, and have no real downsides.
As usually I found some other things that I thought "needed improvement". I wired in some auxiliary small LED spots in the lift gate to go on with when the hatch is opened. No sweat on previous Honda & Subaru. But with the Golf fuses blew, car wouldn't start, & all the other interior lights got all scrambled. Eventually got it things back to original but only after disconnecting the LEDs.
I found the OEM headlights to be quite feeble & the rear red blinkers don't stand out very well in a sea of red brake lights -- Euro head & tail lights seemed like a price but good solution. Also wanted the simple convenience of a self dimming HomeLink rearview mirror & a pop up hatch. After reading hundreds of posts describing the installation of the above items, I decided it was doable but more than I could handle. With a little effort I managed to find a local GTI owner who had done all the above mods & knew how to code as well. Best of all he was willing to help me do the same!
Piece of cake right? Not quite! After about 10 hours of effort I now have working head lights & tail lights that are a pretty good improvement in terms of safety & appearance. But despite several hours of effort the VW accessory mirror isn't working, I don't have back up lights, & my rear view camera is not malfunctioning more often than not. I'm not sure the camera is directly related to the other items but I certainly am suspicious! Now I'm praying that my VW enthusiast helper will be willing to spend a few more hours and can get all the "bugs" worked out. I'm discovering that electronics on VW/Audi are incredible complex compared to Honda & Subaru. Definitely not for the faint of heart!
Regarding the pop up hatch, I got the ECS hatch struts. Install was straight forward but afterward it would release but not pop up, had to code to get that to work. Yes there is considerable more effort required to close the hatch now. But both I & my wife can still do it (we are 67) with one hand and oomph! Worth while addition IMO.
Last but not least, I can't help but wonder if I have a fender-bender & break one of the euro lights how easy it will be to get them replaced & if the insurance will cover the costs.
All that to say these aftermarket mods sound great but be prepared for potential challenges and issues. Best wishes in your pursuit of modding your TSI.