With some extra coding it is well possible, yes. I am werking on sth. similar but a bit more advanced for the core32 at the moment. A few ADSR EGs are certainly doable within the limits of the pic.
I am slowly finishing my first panel of analogue modular synth and my next panel will have a Midibox CORE8 running the SID V2 firmware + AOUT CV board. There is no need for the physical SID chip, PCB etc, you just use a CORE8 and AOUT of your choice but you get access to the SID engine to send to your CV gear.
If you read through the SID V2 manual there is a good explanation of the AOUT modulation capabilities. If I understand it correctly (i.e. I haven’t actually tested it yet) then you can send all of the amazing synth engine stuff from SID V2 to CV outs. That means you get envelopes, wave sequencer and LFOs.
The other possibility would be to use the Analogue toolbox available from the MIOS download page, that has some envelope and LFO to CV stuff. But personally I’m going the SID route, it looks much more interesting
David
ps obviously once nILS finishes his MIOS32 version then these options may increase further.