Installing aftermarket parking sensors

Hello 4R experts,
I am a new owner of 2021 4R SR5 premium. it does not have parking sensors. I asked couple Toyota shops about installing the part from 2022 model on it, since they have same frame, and software, and I got various unclear answers made me confused and wonder if they were telling the truth. one shop said they can install an after market one, but not the EOM one. Which is weird, if they are going to do wiring of a 3rd party supplier anyway, why not install the EOM wiring, it should be more compatible. What am I missing?
I know there is a back up camera, but I am more comfortable with the sensors, specially from the front.
The same story for the blindspot detectors.
Any advice or experience you could share ?
I apologize if this has already been discussed earlier, I tried to find thru the search feature, I did not find any.

 

Are you trying to install the technology package unto your 2021 T4R?

 

If i am not mistaken, the tech pkg (infotainment, auto car play.. etc) is already installed, i have the premium trim.
But it doesn't come with parking sensors nor blind spots detection.

 

Gonna be cheaper and easier to get a 2022 Limited than it is to retrofit BSM and OEM parking sensors onto your current one

 

Could you share why? if an aftermarket retrofit is possible, why not OEM? is it just the price of the OEM one?

 

Parking sensors are only on the Limited. To add them to a lower trim you likely need some of the control modules from a Limited. I have a ‘21 limited and have been poking around under the rear bumper cover for other reasons. Doesn’t look to be any provisions for BSM so to add that you’d need to get a new wiring harness or at least the part for BSM and graft it onto your existing wiring harness and then change out any related control modules. Probably easiest and cheapest way to do so would be strip a crashed one for parts. Still going to be thousands of dollars. Hence cheapest way to get what you want is get a ‘22 Limited which will have both BSM and parking sensors