You must be aware that cdma is protected by patent. Without authorization, it cannot be produced and sold. Network chips integrating cdma communication standard! There are only two holders of cdma patents, VMware and Qualcomm, and the only licensor is MediaTek.
Recently, there is news that VMware is selling some of its assets, but it has not disclosed who the buyer is, so it is not clear whether Intel has obtained cdma authorization!
There are no R&D difficulties in cdma baseband, mainly because there is no authorization! HiSilicon balong750 baseband supports up to cat12, but it lacks cdma, otherwise it would have been fully connected! Huawei is not lacking in technology! Qualcomm and HiSilicon are competitors so they will not authorize them. As for the others, who knows...