I currently use the "Save as Site Template" feature within my SPO Site Collection frequently and apply the Site Template to new subsites under the parent site 7-10 times a week. I have a requirement to create SP environments quickly that house a variety of prepopulated doc libraries, lists, etc. The subsite has 10+ doc libraries with subfolders that house a variety of different artifacts. The ability to save as template and then use that custom template to apply to a new site is extremely useful.
I understand that this feature is being deprecated as MS does not want hierarchial environments (but rather a flat infrastructure).
Are there alternatives to the requirement I have described? Please and thank you!

