So here's what I learned about my 2020 Silverado 1500 LT Texas Edition...
1) When it's day, and just the DRL's are on, they are at their brightest. When the turn signal is on, the DRL's TURN OFF.
2) When it's night, and the lights are on, the DRL's are dimmer. When the turn signal is on, the DRL's DO NOT TURN OFF.
There is a federal law (FMVSS 108) that states when the DRL's can stay on and when they must turn off. Here is a good read that I found... https://jalopnik.com/heres-why-modern-cars-turn-off-one-of-their-lights-when-1792394567
So, I ordered the quoted harness shown above. After installing, I checked all lighting functions and everything worked as normal, and the DRL's DID NOT TURN OFF...even in the day.
And to hopefully not be out of compliance in any way, I ordered these turn signal bulbs from Lasfit. They're designed to avoid any "hyperflash" errors. https://www.lasfit.com/collections/7443/products/lasfit-7440-7441-w21w-led-turn-signal-lights-canbus-error-free
So now, my DRL's stay on ALL THE TIME, and my turn signals are BRIGHT AS HELL without any errors. I'm happy with this modification combination.