is there any particular reason for using gurps instead of cyberpunk red?

On the Gorilla Arms, Ultra-Tech Stats out a pair of bionic arms as Arm ST+2 (Both arms; Temporary Disadvantages, Electrical, -20%, and Maintenance, 1 person, weekly, -5%) [8]; DR 2 (Arms, -20%) [8]; No Fine Manipulators (Mitigator, -70%) [-9]. for a total of 7 points and a cost of $24,000. That's about 6~7 months worth of income to replace both arms on a regular salary, assuming you're using the job rules on Basic Set page 516.

Of course the cash cost should reflect how common or rare you want implants to be. At an arveage monthly income of $3,600, a $500 implant wouldn't be that big of an investment/impact for someone at a status of 0. At most they might have to take on a temp job for a week or two to afford it.

Ultra-Tech's section on Cybernetic starts on page 207, if you want to look at that for a baseline.

The default rules for Obscure [Sense] in Basic Set: Characters says that making it ranged gives it a max range of 100 units, and the affected area is a 2 unit radius, while I’d want to reduce it down to 50 unit range, single-target, and only affect robots and cybernetics. Would these be custom limitations I’d have to make?

Basic Set Page 101 is the start of the Modifiers section and contains a number of Enhancements and Limitations that can be applied to Advantages. Reduced Range (B115) is one of them, Half range would be -10%. Making it only affect Robots would be Accessibility (B110) and would depend on how often robots appear. If you want it to be single target, consider using Affliction (B35) to give the Blindness disadvantage [+50%] instead of Obscure.

Is there anything I’m missing from these lists?

In general, a cybernetic that completely replaces a body part should come with the Disadvantage for not having that body part with the modifier Mitigator (-60% to -70%). This reflects the fact that if the cybernetic breaks, gets hacked, or is otherwise disabled that the character does not have the ability to use that body part.

Just a little bit after I posted this did I even think of making Quickhacks spells, so yea....that's kind of embarrassing. I'll probably make a Cyberdeck implant that allows for "casting" quickhack spells and have different ranks grant bigger spell loadouts.

Though it does raise a different question: would it help reduce the point cost of different implants if they had some kind of limited "spell" effect rather than dealing with trait enhancements and limitations?