It may be a serious question, but I don't know how realistic it is. Folks assume the goobermint has some kind of massive data base somewhere, with a complete list of everyone's firearms purchases through FFLs, going back to when they bought their first .22 rifle from the hardware store. The last I heard, ATF was years behind on processing records from expired/surrendered/deceased FFLs; apparently there are hundreds (maybe thousands?) of cargo containers stuffed with stored/unprocessed FFL records. And even if they eliminated that backlog, the goobermint inventory wouldn't ever be current, complete, or correct...
You appear to be laboring under the delusion that federal agencies feel an obligation to obey the law.
The BATFE is prohibited by law from copying all the information on Form 4473 from FFL dealers, but they do it anyway.
Over the years there have been multiple reports of ATF agents copying the records of FFL dealers right in front of them.
And with most dealers keeping computerized records these days, they are handing it all over when the ATF audits their records.
https://www.ammoland.com/2020/02/atf-proposes-make-national-gun-registry-easier/#axzz6hBTGtlTA
https://www.thetruthaboutguns.com/does-the-atf-already-have-a-national-gun-registry/
https://gunowners.org/does-the-atf-have-a-list-of-guns-that-you-own/