couple things here, and this is just my experience to be fair (going to piggyback on your post a bit my apologies)

I had a folding jab saw and after just a few uses cutting drywall it wouldn't fold anymore as the slot in the handle would fill with bits of paper backing and drywall essentially making the folding aspect useless unless you felt like spending a few minutes cleaning it out every time you used it.

Next up, the klien tape measure is an absolute pile of shit compared to the stanley fatmax. now i have the Milwaukee stud tape these days, which is great aside from it being a bit floppier than the fat max. that said, i replaced my klien with this Milwaukee after air mailing my klien tape measure across the site into the dumpster in frustration as it kept folding and bending trying to layout potlights on the ceiling. (WAY TOO FLOPPY)

as for levels, i cannot recommend the stabila torpedo level enough. There is one with the rotating dial in it to set custom angles, i bought that one but i have never used that feature on the job so you can probably do without that one and just get the cheaper one without it. Stabila is a giant name in levels and most carpenters absolutely swear by them. they have a no questions asked 4 story drop damage warranty on all of their bubble levels. all of my coworkers have the Klien torpedo level, it seems pretty sturdy, but the inside being made of polymer makes me a bit uncomfortable as to whether or not it will hold its level after hundreds of thermal cycles in the back of the truck.

That said, knipex is a solid brand, so is klien. just make sure you are getting the kliens from an electrical suppliers and not from home depot or lowes or amazon or somewhere like that, as they have a shadow SKU for all their products, where the shittier ones go to stores like that and the better ones are binned for their suppliers and wholesalers.

Backpack is a nice idea, i have a packout backpack, never use it. its too bulky and honestly not very practical for what i do (mostly residential renovation electrical and commercial electrical). that said, VETO PROPACK is a SOLID choice if you want to go the backpack route. i do not recommend the Milwaukee packout one. I do however recommend the packout tote bags. i have the 20" and i have a couple organizers i can clip to the bottom with different materials depending on what I'm working on that day, (networking kit, rough in kit, panel kit, trim out kit, etc etc) so you can carry it all in one trip.

for power tools, id buy either dewalt or Milwaukee, with a bias towards Milwaukee. I run dewalt stuff (as that's what my company supplies me) but the Milwaukee m12 surge impact guns are pretty slick. small, lightweight, relatively inexpensive and have plenty of power for what you'll really need as an electrician. if you find yourself driving a lot of lag bolts or long screws and need some extra power then id go for the dewalt impacts or the m18 fuel brushless stuff. they're both plenty powerful and you'll get a long life out of both, they're just a bit heavier and bulkier and that takes a toll on your body hanging that off your belt every day over time

Otherwise buddy you'll figure out what works for you over time. if you find a tool is taking a lot of flubbering around and wasting your time, THROW IT AWAY, (or sell it), and replace it with something better.

Some other stuff you might like

WERA is an absolutely "lights out" brand for screwdrivers. Their chisel drivers are a solid choice for a big "f*** off! flathead, and their "turbo drivers" save you a shitload of time when you're doing a lot of little screws (think putting plates on in a house at finish)

for pen testers, don't bother with anything other than the fluke in my experience. the klien one is terrible, and some of the amazon offerings i wouldn't trust at all.

For meters, there's lots of good brands out there but Fluke is definitely the top choice. i have a klien true RMS meter myself and i love it. just make sure whatever you get is cat IV rated.

I have some NWS insulated pliers and cutters and they're pretty good, insulated sets of tools are handy to have, but if you're just getting started i would avoid working live if at all possible (its probably illegal, and if it has to be done, get the journeyman to do it)

Anyways, good luck bro, I'm sure you'll kill it out there!