How to export a modern site including everything in the site contents and then import it to a new tenant?

"However, as per the official Microsoft article, it says the Save As site template can be used only on the SharePoint Online teams site where it doesn’t support on the Communication Sites."

I reported this inaccurate information years ago - why hasn't it been corrected so users don't have to waste their time asking this question?

Dear Aditya Biswas

Good day!!

Apologies for the inconvenience caused and please don’t worry, let’s work together on your concern and move towards a resolution path.

I understand your concern and to my knowledge, to create a new SharePoint Online site from the existing SharePoint Online site, we need to save the site as a template and download the template from the Solution gallery, then import the downloaded the template to another Office 365 tenant.

However, as per the official Microsoft article, it says the Save As site template can be used only on the SharePoint Online teams site where it doesn’t support on the Communication Sites.

But to my search, we can save the communication site as a template via accessing the page using the URL, so suggest you try the below steps and check the outcome:

Steps on saving the site as a template:

Step 1: Enable Custom Script on the Site Level: Allow or prevent custom script - SharePoint in Microsoft 365 | Microsoft Learn

Step 2: Go to the SharePoint Online Communication Site> Paste the following path “/_layouts/15/savetmpl.aspx” at the end of Communication Site.

Note: The URL looks like: https://tenantname.sharepoint.com/sites/sitename/_layouts/15/savetmpl.aspx

Step 3: Fill the details and make sure to enable “Include Content”> Click OK

Note: After you click on OK, it will give the following page:

Step 4: Click on the Solution Gallery> Click on the template name where it will download WSP file with template name.

Now creating a SharePoint Online site from the downloaded template:

Step 1: Access the other tenant with admin user account.

Step 2: Go to the SharePoint Online admin center> Active Sites> Create Site> Browser more sites> In the drop down, select More templates.

Step 3: In the Create Site Collection page, fill the details and make sure to select the template as following> Click OK for creation of site.

Step 4: Let the page redirect to the SharePoint Online admin center automatically> Wait for some time and go back to SharePoint Online admin center> Active Sites> Filter the site template to Empty> Click on the URL> In the template selection page, click on Solution Gallery> Upload Solution> Select the downloaded template> Open> Click OK> Activate the uploaded solution.

If the above steps didn’t help to meet your requirement, we apologize the above steps are the only out of the box solution. If you are also okay with non out of the box method such as PowerShell or Rest API, I request you to post your concern in the related Microsoft community i.e., Questions - Microsoft Q&A with SharePoint Development tag to get the detailed help from the experts.

Apologies for redirecting you to a different community as the members in the category posted focus on the users with the out-of-the box concerns and have limited knowledge on PowerShell and Rest API, so to get the fast and better assistance, we have redirected you to the correct community.

Appreciate your patience and understanding. Have a great day!!

Best Regards,

Sophia