No really related to the other thread on Monterey having errors opening files which opened on my 2007 iMac. I have old files created by MacWrite, Microsoft Works, Pagemaker, Simpletext, Excel (version 1.0) which either I use a document converter or get some of my old Macs -- some real classics from 1985-87 -- running to open, update and then move by "sneaker net" (floppy disks) to newer Macs, then newer yet Macs, eventually by stages getting their contents readable on this new iMac.
I have Word 97-2004 and word 6.0/95 which open with Word 14.1 but at least those I can have Word save them in its docx format. Same with my Excel 97-2004 files created on my Mac SE/30 in 1992 which Excel 14.1 will open and save in xlsx.
A document converter would make it so much easier.