Salesforce Data Cloud //
1st Party Cookie & EventPush
Page load --> GTM fires Tag and Cookie with VisitorId is set
Enter a value in textfield and click Button --> DataLayerEvent with VisitorId and textfield-value is pushed to GTM
GTM fires ServerSide-Tag to Webhook/GoogleSheets/(Salesforce Data Cloud) --> Record in Google Sheets Table is set
Cookie is set from GTM after initial Pageload. Check DevMode/Cookies and refresh the page.