Nextcloud works well for this, and as the files are already on your server you don't have to upload anywhere, you just share the folder, put an expiry date on and send them the url
That said, I've had updates (across major versions) break things on multiple occasions, one out of two servers running the exact same version has random crashes and in addition to that the file locking by default (if enabled, but not using Redis: https://docs.nextcloud.com/server/latest/admin_manual/config...) has broken and prevents me from deleting a file that just sits there and takes up a few GB of space. Oh and their Android app fails to upload files if I use the share option, instead of the file picker from within the app.
On the other hand, sure beats storing data on third party clouds and is free, so I'll still keep using it.
And this is how some company can accidentally see way more than it had should.
Never do this for anything remotely important, just add a separate 'Share' folder and allow sharing to external users only from it.
Don't forget, if the user can't see something on the server that doesn't mean there is nothing else there. Eg: ABE enabled SMB share.
I've had that with both mail clients and messenger. Call it antivirus protections, "you're leaving our website" thing, facebook tracking data... Whatever, they will break your links eventually.
I know, it's unbelievable, I don't blame you for doubting me. But still...