Listen to this advice.
I had a system that has ~600gb of blob data in bytea that could have easily been an S3 bucket + db reference. It made backups way more of a pain than necessary.
It was intentional in the design, because I wanted total consistency with a single backup for the system. It worked great for years. But as we got more and more clients, it really should have been migrated to the above design to make sure our backups could be taken / restored faster.
So the original advice actually still stands. You can still start off with Posgres, store it in BYTEA columns, and then work on a plan to use an object storage as you grow. S3 may not be possible and you will be evaluating other options like Minio