The M.2-to-SATA adapters are designed to support M.2 SATA SSDs. You have a M.2 NVMe SSD, so you cannot use this option.
My opinion? Remove the Optane memory card and install the M.2 NVMe SSD.
Optane memory is designed to improve the performance of a HDD, by adding a very smart, high-speed cache, in order to achieve SSD-level performance. But, the maximum performance of this solution will not (IMHO) come anywhere near the performance of a good NVMe SSD. You have the good NVMe SSD, so use it. Yes, you paid for the Optane card, and that's a shame, but you really don't need it if you are using a NVMe SSD.
Hope this helps,
Thank you Scott for your answer. I'll follow your suggestion.