Another option is to create a Microsoft 365 Business tenant, with a single Business Basic license you get 1TB OneDrive storage and 1TB Sharepoint storage - their ToS says not to use customer data in AI training.
Unless you already know how to manage it this is probably as cumbersome as selfhosting though.
I have no idea about their ToS against non business licenses, so this assumes spending for a business basic license.
If you aren't behind CGNAT you can use dyndns to get around not having a static ip if you want to get into selfhosting with proper external access. I doubt you'll have the time with a newborn though. :)