A few comments. I won't quote what I'm responding to, hopefully it's not too confusing.
Think of a patch cable coming from an audio source in your rack as a VERY LOUD signal. You just have to get the right plug on the other end, put it into your mixer or Digitakt input after having turned the level to zero, then slowly turn it up to taste. An output module will mean you're not tied to your mixer or Digitakt. Convenience, not necessity.
You can use Pam's to quantize an external signal. But it wasn't made for that purpose, the manufacturer says there could be latency issues, and it uses up one or both of the CV inputs. I've been considering uO_c for quantization and what is commonly but incorrectly called a Turing machine, but I'm also considering other options. My sequencers already quantize; I need a quantizer for CV that isn't coming out of a sequencer. You don't need a quantizer for MD if you're willing to tune by ear and not use "shred" randomization. But if you need to quantize MD to use it (say, to alter a melodic sequence on the fly), then maybe think about a different sequencer.
"Menu-diving" covers a host of usability issues, and they're different for different modules. The issue with Pam's is that most interaction is done with a single push encoder. It does about as well as it can given that limitation, it does a lot of very useful things, and the menu structure isn't too deep. But going between the channel overview and a particular channel's parameters is a one-second long press. That's longer than it sounds in practice, and really breaks up the interaction. It wouldn't be easy to, say, tweak two separate Euclidean rhythms. I haven't used uO_c, but based on the documentation, the issue there is more with a complicated menu structure. There are two buttons and two knobs, so the interaction will be quicker in one sense, but longer in different ways. Quantization is usually set-and-forget, but other functions might need more tweaking while playing.
I have the Intellijel Quad VCA, but am still considering Veils 2020, because the sliders on Veils 2020 correspond to the small attenuators on the IJ, which I use more than the large level knobs. There are a lot of VCAs out there, so maybe you can tell us which ones are available at your retailers of choice?
It's hard to see the modules in the first video (except for the Verbos Complex Oscillator, MD, and Morphagene) but the patch notes are pretty good. Both videos rely on effects: just a delay in the second one (and I can't see the patching but I don't think it's doing anything too complicated) but Clouds and Morphagene in the first, so delay, reverb, granular, loop manipulation. If that's part of the sound you want, then you need to think about how to achieve it. FX Aid XL will get you part of the way there... but it's another Happy Nerding module, so it may be hard for you to acquire. You also have the Elektron effects at end of chain, and I guess the mixer effects if you want to use those. Between the Elektron effects and a good external pedal I have (plus a send/return module so I can put that in the middle rather than only at end of chain), I find it hard to justify any in-rack effects currently, and that doesn't even take into account the ability to use my laptop or iPad in various ways. The one exception is an analog BBD delay (Sarajewo). But that's me; your needs are different.