Hi @James Amor,
Thanks for reaching out to us. We are very pleased to support you.
We need to use PowerShell for this template configuration. Please make sure you are a SharePoint administrator. If you are not, please contact your SharePoint administrator.
Step1: Download and install the SharePoint Online Management Shell.
If you already have a previous version of the shell installed, uninstall it first and then install the latest version.
Step2: Connect to SharePoint Online.
Open the SharePoint Online Management Shell and connect to your SharePoint tenant using the following command:
Connect-SPOService -Url https://<your tenant>-admin.sharepoint.com
Step3: Get the Site Script from the Existing Site:
Use the Get-SPOSiteScriptFromWeb
cmdlet to extract the site script from your existing site. This script will include all the customizations you made to the site. The parameters of the command can be adjusted, you can refer to this article to adjust your parameters.
$SiteSchema = Get-SPOSiteScriptFromWeb -WebUrl https://<your-site-url> -IncludeBranding -IncludeTheme -IncludeRegionalSettings -IncludeLinksToExportedItems -IncludeSiteExternalSharingCapability -IncludedLists ("Lists/YourList")
Step4: Add the Site Script.
Add the extracted site script to your tenant using the Add-SPOSiteScript
cmdlet.
$SiteScript = Add-SPOSiteScript -Title "Your Site Template" -Content $SiteSchema
Step5: Create a Site Design.
Create a site design using the site script you added. This will make the template available in the "From your organization" tab.
-webTemplate: Use the value 64 for the Team site template, and the value 68 for the Communication site template.
You can refer to this article to learn more about this cmdlet's parameters.
Add-SPOSiteDesign -Title "Your Site Template" -WebTemplate 64 -SiteScripts $SiteScript.Id
Here you can see your site template under Organization tab.
If you have any questions, please do not hesitate to contact me.
Moreover, if the issue can be fixed successfully, please click "Accept Answer" so that we can better archive the case and the other community members who are suffering the same issue can benefit from it.
Your kind contribution is much appreciated.