The reason is mainly limitations on CPU level. Only high-end/flagship CPUs (used on phones priced at 800$+ on average) can support true global band connectivity. The BraX3 CPU (Dimensity 6300) has a limitation on the number of bands supported on it. We tried to select the bands so that the BraX3 can provide decent connectivity at almost any point in the world. As a result we had to do some trade offs (e.g. not supporting verizon bands, dropping some other bands like the B20 and B32 you mentioned, etc.).
We’re not at the scale currently where we can support multiple variations of the BraX3.