The PMS-2 is going to be out of stock for likely a long time, while the PMS-Lite is still being restocked pretty frequently. I would just get a Lite the next time it's in stock as the differences are pretty minor and they mostly function the same.
Me personally I'm waiting for the PMS-Lite to come back in stock before starting, because I want to make sure my trim even boots before going any further.
They're out of stock because of the chip shortage, so I doubt it would be any easier to find the chips yourself, not to mention the hassle of assembling the board. I'd just wait if I was you man.
The PD 2 is needs to go with the PMS 2 or the PMS Lite in order to function I believe, however someone correct me if im wrong. Also have you thought of what you're going to do for a display?
I originally got interested in portables a couple years ago but felt that it was way too difficult for someone like me with no experience or knowledge about electronics prior, but just recently I thought about actually giving it a go. I decided on an Ashida because it's an amazing design with...