I have seen the LY68L6400S mentioned before, but found no confirmation if they were in fact a valid alternate so I brought some in to test since chip shortages are going to be around for awhile.

These appear to be the exact same as the ESP PSRAM64H and have the same chip ID.

You do want the 'S' version for the SOIC. The 'B' version is the WSON package. Here is the Datasheet

Tested 5 chips on 5 Teensy 4.1 using the standard PJRC teensy41_psram_memtest and they work fine.

Available from LCSC, Aliexpress and ProtoSupplies.com will be adding them to our mix of products as well.

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--- Ken