Considering it is a work in progress and a device for the aficionado the really interested should have no problem paying before production starts.
Payment is rarely the problem in such cases, it's more of a stalled development process that no one can say will ever complete. Based on the pace so far, you have a good chance that it will be completed around the first quarter of 2023.
1 - software development, sorry I am not proficient enough on the subject to usefully participate.
2 - hardware business case and funding, i am happy to pay for issue 2 if it helps to support development (issue 1), I guess many others will also
My proposal was only for issue 2 and if you want a complete calculator now just buy a DM42 of DM41.
Our top priority problem (for Americans: challenge), however, is time for software. It is so throughout this project. Thus, whoever can devote time for writing software will be most appreciated. Right now, our software department consists of Martin and Friedrich working on the 43S in their spare time which is obviously less than 1 FTE (full time equivalent). This department can certainly take support. We will, however, never be able to pay anybody for programming - you can just earn fame in the community, though this for sure.
The other tasks (like project control, administration, documentation, etc.) are taken care of sufficiently so far.