My only near-excursion into modular was with the Moogerfoogers. I got the MF-101 low-pass filter and MF-103 phaser in 2002 (before Bob Moog got the rights to the Moog name back, so the company they were initially produced under was called Big Briar). I didn't really know what I was getting, I thought they were just effects, but the manuals had a great intro to modular synthesis, and within a couple of years (and after acquiring the CP-251 control processor and MF-104 analog delay) I was making boops and beeps just with those four units connected to each other. Isn't that kind of the crux of the biscuit? If your effects can be used to control each other via control voltage (CV) then they can be kind of a pseudo-modular system, but if each effect is only doing its thing internally, then it's not. (Of course there's more to it than that but it's one basic way to look at it)
@ugly_bassplayer inspired me to delve back into some "weirder" sounds recently, so yesterday I used the smoothed-out sample & hold from the CP-251 to control the low-pass filter frequency in my Frostwave Resonator that was being fed fretless bass through a Mastotron fuzz. I might try again - the frequency range was a little too wide, so I might try again but using an attenuator in the CP-251 to reel it in a bit. Not super-modular, but I don't have any pedals to do random sweep of the filter frequency, so it's fun to use moogerfoogers to control it. I've also used the LFO of the MF-103 phaser to control filter frequency - the CP-251 has spitters too so I can take the LFO and split it to two filters and sweep them separately.
I need to take a big picture of my Big Briar stuff!