does anyone know what the ratio of non-showdown to showdown profit should be in optimal NL? PLO?

out of 100% of profit, how much is coming from showdowns/all-ins and how much is coming from non-showdown (making villain fold). Does anyone know the answer?

There's no optimal ratio.

Most of the spots that affect the red:blue line ratio are ~0EV bet/check or Call/fold spots.

It's usually optimal for your blue line to be negative. Depends a lot on your opponents though.

I'm guessing you meant red.
@ OP: Most (but not all) winning players have a negative redline for non-showdown, so you can't really have a ratio between blue and red, because the former is usually positive and the latter negative.
Very occasionally, however, an aggro crusher will have a redline that is higher than the blueline. :/
If you want to compare your SD and Non-showdown lines to other regs, you can look at their graphs in various stats threads and calculate their winrates/lossrates for those graph lines. I don't have time to look now, but I would be extremely happy if my red line was only going down at -7bb/100. It's actually much worse than that, but the blue line towers so far above everything else that I don't really care.

I meant red*, my bad.

Most people that have a positive red line are whales/fish.

Agreed. It's just people like Linus (who reportedly has a positive redline) that are extreme outliers!

My ‘went to showdown’ is around 30-35%. My won when saw showdown is at 50-60%.

My winrate is derived mostly from blueline winnings and a small portion of redline.

In my experience a redline takes a lot more effort to build and I get better result of just focusing on blueline. blueline pots will always be the biggest.