We have created a new Sharepoint Online tenant with flat modern organisation for a charity. However this requires various cross site lookups. I have investigated various options but cannot get any to work. It seems that most solutions relate to SharePoint 2016.
I have tried adding items to the Content Type Gallery but cannot find a way to connect the columns to a list on a specific site. I realise that we will need many central data resources that can be looked up from any site.