You are looking for details on the phenomenon of data remanence. There is not much data freely available.
The semi manufacturers have little incentive to perform in-depth testing, There are no financial benefits, and their findings may contradict their claims regarding secure erasure.
Likewise, system integrators have no incentive to share their findings with potential competitors.
I assume intelligence agencies have programs for this, but they will never disclose significant details---at least not while they are relevant.
This leaves academic sources as your best bet. Unfortunately, academic articles are often hidden behind paywalls and/or only discoverable via subscription services. Universities pay for access as a basic cost of running their business, but it is not particularly affordable for individuals.
In the rare event an article such as this one is published as "open access", then it is available without a subscription to the publishing journal or the academic database(s) which include that journal.
From the link to the publisher's details, you can see that only 5 articles from the Journal of Hardware and Systems Security are open access. That is not even one full issue.
If you have an affiliation with a university or a company that is willing to provide access, there are hardware/systems security publications that likely contain the information you seek---without that, you likely need to experiment personally.