If you want two different apps to share the same data, then the easiest way is to use the same Google Spreadsheet for both.
If they aren’t using the same Google Spreadsheet, then you can move data between the two spreadsheets, so that one app has a read only copy of data from the other app. The easiest way to do this is with the IMPORTRANGE() function.
Easy! I do this for some of my apps. The simplest way is to point both apps at the same G Sheet. That way the connection is instantaneous. The other way is to IMPORTRANGE between Gsheets (or similar). And I think you can link Glide Tables together too.
Two separate apps can share the same data, but they cannot share the same computed columns. So you can’t share things like relations, lookups, rollups, etc. All of these types of columns are dynamically created on each users device, so they are specific to both the app and the user.
Within an app, you can link tables together by using a relation. If you are referring to multiple apps using the same glide table, then you can add existing tables to any app and the data is shared between them.