Thanks, but…
Result is the same: No code that involves Wire.write() results in SDA and SCL pins wiggling. (And endTransmission() returns a value of 4).
The bottom line is: The same sequence (byte-at-a-time or bytes in an array or string literal) that works for me on other Arduino boards, including the Nano RP2040 Connect, does NOT work on the XIAO RP2040. Since the RP2040 hardware I2C interface is OK, I believe there is an “Issue” with the Seeed software in the board package for the XIAO RP2040.
Period. Full Stop.
Regards,
Dave