first of all: shame and blame on me; I have a huge amount of disk space and an LTO5 library: I am the only one to blame but that's not the topic. Won't get through why at the moment I didn't have a 2nd (and 3rd) copy of that data, which I should have had.
Starting scenario: laptop with 1TB system NVMe and 2TB data NVMe. Data NVMe had a 60GB unused (ex linux) partition and the rest as NTFS. I swapped the 1TB driev with a twin 2TB NVMe and, you see it coming, I repartitioned what I was persuaded to be the system NVME and installed windows on it. I booted and realized I had just zapped the data NVMe.
Tried PhotoRec/TestDisk with mixed results. I'm looking for more advanced techniques to recover the data considering what I car the most are Sony RAW files (about 600GB) of all the photos I shot (amateur photographer). So we know the file format and the fix size of each file (including its structure). We also know the empty beginning partition was between 60 and 64GB (no software found the original data partition being an NTFS partition of 2TB-60/64GB at the beginning.
I've been in IT for more than 28 years: every pointer to whatever can be tried will be welcome. of course I created a binary copy of the NVMe to prevent further damage. Thanks to everyone who'll take the time to help!