Fully possible, time consuming as mentioned and to what extent depends how big your runtime actually is. Some people are under the impression they have a gigantic Runtime around 250gb or so until they cross path with the dude who has 8-10TB.
However, there are tools that will ease this process a lot for you. Get "Content Gatherer" and "DAZ Advanced Library Manager". The latter is available for free the other you can find here. Google is your friend.
There are many different ways to approach this but focus on the tools they provide for analyzing your products installed and what references they have. Use the "Installation Helper" utility available in Advanced Library to analyze your runtime.
Exporting your product items becomes quite easy with Content Gatherer once you have a good overview where your main product files are at and which products you actually have installed. Content Gatherer will do the most time consuming work automatically for you and can export out the complete directory structure for your items. If you want to repackage them as DIM use "Content Package Assist" you can find it here also.
Also, unless you manually deleted. Every item what you have installed in your runtime using the DIM app will have their index files sitting on your harddrive (is a cleartext file with all metadata for your product and all files and paths for it) if u have a little coding or scripting skills with Python for instance, you could automate a parser that will "regenerate" all those back to zip files with correct folder structures etc.
Could recommend P3dO Explorer here also, but for full functionality u need to buy a pro license. The version available here is old and obsolete and the free version lacks the functions that would be of any greater help in this case. Its well worth the money though if u ask me.