Found
this thread which clarifies pink and red can be mixed, per March 22, 2002 Toyota TSB:
A new pink colored LLC is being phased into production for all 2002 Japan Built
Toyota models. The color change does not affect the maintenance procedures or
intervals established for the red coolant. The new pink coolant is 100% compatible
with the current red coolant and red coolant can be used to replace, top off, or mix in
with the pink coolant with no adverse effects.
Now I feel better about not worrying about that last ~gallon in heater lines, even in the off chance it was red.
So it was probably already overkill to do 3 distilled water flushes from all 3 drain plugs lol (that passenger side engine block is a PITA!). But oh well, got a cleaner system now for it.