A Pi Zero W would be enough to get some basic formant synthesis going in csound. I'm hoping they make another Zero with a faster engine in the next 2 years.
I'm told Csound is easier to get into these days. I last tried it in 1995 on a SGI.
Csound is cool, partly because it is based on the very first Music languages back when a 'mini-computer' meant something the size of a large fridge.
Also, there are some raspberry Pi OS images that can load VST synths, effects etc. so that might be a way to get something cheaply into your AE rack. I have not investigated this enough to recommend anything yet though.
I think the Teensy 4.0 and 4.1 might be able to do it, so some extent.
There is some discussion here and it looks like waiting a bit for people to port various libraries over to the newer architecture would be the easiest path. It would be nice to have a gender control on a filter.