In 1991 I ported the Motorola freeware cross-assemblers to MPW on the Macintosh, merged them, and added a bunch of enhancements, resulting in asm68. In the mid-90s PIC support was added and it was ported to Linux.
Someone on Usenet was asking for a Linux version of the as09 freeware assembler. I don’t think I have a copy of the original, but I found my old asm68 sources, dusted them off, fixed some warnings, and put it on my web site.