BSM aftermarket kit? (Blind Spot Monitor) 2021

Anything new on Aftermarket Blind Spot Monitoring systems? Getting a new used prius.... looks like I am going older and cheaper. Sunroof instead of rare tech. But I want that BSM. Would like to know if there are any tried and true systems any forum users may have experience with.

Thanks in advance.

I may actually get a garage for a week to
1) install sound dampening
2) Possibly a rear, inside, and forward dashcam system (Vantru)
3) BSM aftermarket kit.
4)??? LED headlights or fog lights or lights to illuminate into turns. (like the old cadillacs used to have.)

Might as well do it all at once. Probably going to focus on the wheel wells, trunk space and doors... maybe the floors. maybe the roof.