Good to hear your teams are actively working on this possibility. Hope to see the same for testing!
Ideally, the app creators have option to save or not the attachment file to somewhere in Drive (possibly inside the app default folder?). Once the option is turned on, then attachment files are automatically archived into such folder. Then the attachment file column (Enumlist or List type) would yield array (list in terms of AppSheet terms) such as ; -
DocId=xxxxx, DocId=yyyyy, DocId=zzzzzz
rather than relative paths to reach out those file.
File reference using FILE id is make our life more easy.