Preview v Affinity Photo
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Although Affinity photo version 1 will convert my Fujifilm camera RAW and Apple iPhone HEIC files, it will not convert the Fujifilm camera HEIC files (but the camera is new and not listed as supported for version 2 yet.)
Preview however converts both types of HEIC files (although not my RAW) and has a batch processing facility. By selecting all the required files in Finder and opening them all if they are selected in the sidebar (Command-A) then Export... will perform a batch process on them all. (Use option to determine where they are saved and the format)