Nextcloud supports webdav, which you can just mount as a virtual filesystem either with GVFS or some KIO slave.
AFAIR there is a fuse implementation as well.
For your single application a Windows VM may be suitable. Maybe even on some remote system in your company cloud. Single application forwarding is a long established technique.
For IrfanView itself I don’t know the capabilities, so can’t advise on it.
Nextcloud supports webdav, which you can just mount as a virtual filesystem either with GVFS or some KIO slave. AFAIR there is a fuse implementation as well.
For your single application a Windows VM may be suitable. Maybe even on some remote system in your company cloud. Single application forwarding is a long established technique.
For IrfanView itself I don’t know the capabilities, so can’t advise on it.