Ok...I guess I knew that. I should have asked if anyone knew of any examples of Serum, organic-y, etc...
The video below should give you the overall idea...
A few more thing you can try take it further are...
Export or record some oscillator cycles from a few vintage emulations or sample libraries (Uno-X, Omnisphere's vintage wavetables, UVI/Syntronik/etc sampled vintage instruments etc...) There are also some vintage wavetables for Serum floating around out there as well, (not sure if any of them are properly licensed though...)
Use a noise LFO instead of a Sine, set with the slightest depth, ultra slow, on a few random parameters for more instability...
Roll off top end above 12k-ish with any of Serums filters or high shelving EQ.
Use key tracking to trigger the slight amounts of randomness as you change keys.
Sample, export, or track down some lofi noise. (Tape machines, cassettes, shitty converters, etc), and use them as Serum's noise oscillator... If you wanr to get more
authentic you can modulate its level, pitch, keytracking, and/or start point so it behaves with tiny amounts of variable lofi noise...
And, if you want add another layer of crust... TAL has a snazzy little lofi sampler converter emulation plugin... TAL-DAC. (Free if you have TAL Sampler). XLN's RC-20 is great too. (One of my favorite choices for giving something a little stale crust around the edges...)