If you want to check by your own means if the secure erase has been successful, then you can always try to use some file restoration tools or, certainly better, directly edit the disk and manually check it.
However, there is still some trust remaining toward the disk manufacturer. Without mentioning backdoors, and sadly there are some, there are also simple bogus or inefficient implementation which may not delete the data as securely as expected.
If this uncertainty is not acceptable for you, there is still another possibility on which you can safely rely. No need to trust any hardware or software provider, a method used by major governmental and military organizations to discard disks containing sensible data, and even more it is free if you do it yourself: shredding the disk. I mean physically shredding it. For microship based memory like are SSD it seems the more suitable would be an electrical drill drilling a hole in each chip, possibly accompanied by a sander applied on the circuitry to finish the job. This would indeed provide a good guaranty that no data will be ever recoverable.
However, if you would-like to keep your disk intact, then you will have to cope with some uncertainty regarding the possible data restoration. Nevertheless, I think that a conventional disk wipe (ie. fill several successive times the disk with the total amount of data it can store) followed by a secure erase should be sufficient for most personal use-cases.