We have already built our own compiler, it's just that a lot of work has to be done to deduplicate expressions (in part because references are stored in A1 form, this is also part of why it takes about 15 seconds to unzip the ODS and parse the XML), and even more to consolidate intermediate cells, and dirty prologues/epilogues on tables don't help (because they often mean the first cycle will be odd).

With explicit cycles, most of that work can be avoided.

Furthermore, explicit row iteration means that you can attach reductions to the generator based on the range (i.e. you have a GEOMEAN and a SUM with a statically known range), which often means you don't need to store the results of the iteration, and that also you don't have to compromise between AOS/SOA storage for reductions that can be run with the generator.

Static primitive, option, and union types are also a goal. You can think of standard Excel/Calc values as a tagged union Option type.

Also relying on Windows or macOS to edit our core sheet is kinda out of the question. None of our developers even run windows, and the majority don't even run macOS. Two of us came from a company that did that, and the Excel virtual machines were always finicky there.