sharepoint online – Content type and possibility of reusing the site column in the flat structure

About 6 months ago, I wrote this question about the possibility of reusing content types and site columns among site collections connected to a hub site in the world of flat structure. Migration of our local sub-sites to become collections of modern sites. how we are going to handle content types and site columns. I compared the horizontal structure with the subsites approach, where, in the subsites approach, we can manage the columns and types of site content on the root site and reuse all the columns and the content types of the site automatically within the subsites. So, after 6 months, improvements have been made or are there approaches in SharePoint Online that could allow us to facilitate the reuse of content types and site columns in the flat structure? or the same old case applies, should we use power-shell to handle the same types of content and the same site columns in the site collection of the flat structure?
Of course, I excluded the option of using content type hub sites to allow the reuse of content type in hub sites, because the content type site approach is a very classic / old approach that we should not use with the hub site. as if I had the decision to use sub-site approaches or to use hub-sites with content hubs, I will go with the subsites approach.
Thank you

Reusing connected user fields in the customer profile?

Is it possible to reuse the information of registered users in the customer profile?
for example. [current-user:display-name] in the default value. I have tried this, but I do not manage to make it appear in the cash register. I use the customer profile.