Import from Notion
Export your Notion workspace as Markdown and CSV, then open that folder in Moss.
Export your workspace from Notion
In Notion, open Settings in the sidebar, then open Workspace → General.
Click Export all workspace content.
Choose Markdown & CSV.
Notion will send you an email with a link to download the export as a .zip file. Download it, unzip it, then move the folder out of Downloads into a more permanent location before opening it in Moss.
Open the unzipped export folder in Moss
In Moss, use File → Open... and choose the unzipped Notion export folder. Choose the folder itself, not a single .md file inside it.
In a Notion export, a page often appears as a Markdown file with the page title plus a Notion ID, for example Test 2a2a7e0bad6d803ea747ee5fcfd92153.md plus a folder named after the page title, such as Test/ . That folder can contain image files and database CSV files that the Markdown page links to, so it is important to open the entire unzipped Notion export folder in Moss so everything in a page is imported correctly in Moss.
Once you open the folder in Moss, all of your pages will appear as notes under External.

Import databases
After your Notion export is open in Moss under External, open Settings and add that same unzipped Notion export folder under Connected Folders. Connected Folders give Moss read-only access to the CSV files in that folder.

Open one of the imported Notion pages in Moss. Then press Cmd+K to open the Actions input. This is how you talk to the Moss agent.
Tell the Moss agent to find the database links in the current note, read the CSV file each link points to in @Notion Export, and replace those links with content from those CSV files.
When you mention the Notion export folder, type @ and mention it by name, then select the result that appears under Connected Folders in the typeahead. This gives the agent read-only access to the CSV files in that same export folder.
Example: “Find every [database](...) link in this note, read the CSV file each link points to in @Notion Export, then replace each link with a Moss table of the CSV content.”

You can tell the Moss agent to import database information in whatever format you want, such as tables, summaries, or multiple notes organized into folders. See the Features page for examples of what Moss can create.
You can also tell the Moss agent to replace all database links in all notes in the exported folder. Note: this may take a few minutes depending on the size of the Notion workspace you exported.
Alternatively, you could also have a coding agent write a script that does this.