I wrote this question about 6 months ago about the ability to reuse content types and site columns among site collections that are connected to a hub site in the Flat structure world Migrating our on-premises sub-sites to be modern site collections. how we will be managing the content types and site columns. I were comparing the flat structure with the sub-sites appraoch, where in the sub-sites appraoch we can manage the site columns and content types at the root site and reuse all the site columns and content types automatically inside the sub-sites. so after 6 months have any improvement or are there any approaches inside sharepoint online that can allow us to facilitate content types and site columns re-usability inside the flat structure? or the same old case applies, that we should use power-shell to manage the same content types and site columns among site collection in the flat structure? of course i am excluding the option to use content type hub sites to enable content type re-usability inside hub sites, as content type hub sites appraoch is very classic/old approach that we should not use with the hub site. as if i have the decision to use the sub-sites approaches or to use hub-sites with content type hubs, i will go with the sub-sites appraoch.. Thanks
Content Type Hub is the current solution for pushing CT/Site Columns to all sites, Modern and Classic.
The alternative is to use a Site Design script and reapply it to all appropriate sites when a CT/Site Column changes.