Thanks to all the input I have had from the people who have replied to this thread.
I have started the import of my 160k+ images.
Once this is done I will have a very good alternative to Lightroom Catalogs. I need to check and see the differences.
I have reviewed and tried to replicate all the various options and have decided that I still think a File Browser panel would be a wonderful addition as I dont always want to ‘Import’ my images to a catalog but still may wish to edit the odd image on the fly that lives in a separate folder or directory.
Thank you all for you very helpful and rapid response to my question. I look forward to Darktable v3.6 but at present I am very happy with v3.4