Finally got around to implementing it - should be doable in 0.0.52+ via color/
signal prefixes.
For example: out['red/signal-A'], out['green/signal-A'] = 5, 11
(colors can be renamed in mod settings, but red/green will always work as a fallback regardless)
Decided to stick with using same "out" variable for all wires there so that old stuff like out = {}
will still clear all outputs, same as before.
Both "signal-X" and "red/signal-X" can be set, in which case "red" version will override generic one on that wire, and the fact that these values are persistent would mean that just setting "signal-X" anytime later will have no effect on red wire until "red/signal-X" is unset, which can be a bit counter-intuitive.
Output signals are displayed with color coding if red/green values differ, which should hopefully make it pretty clear when something is overidden per-wire. Though these outputs are queried from resulting combinator settings, so should display any red=green values with non-color-coded "[out]" prefix, even if these were set separately.