So…
With the ginormous caveat that we haven’t tested this at all.
One of our customers who has an SLS (but MS says the relevant hardware/software is the same with the Pro 8 and SLS)
The customer has tried altering in this HKEY the dword value in the “lastattemptstatus” from the default value of 0 to a value 1.
Computer\HKEY_LOCAL_MACHINE\HARDWARE\UEFI\ESRT\
According to the customer this seems to “reset” the smart charging software/hardware. In other words, it likely won’t enable smart charging immediately but after the system goes through the cycles it would do when brand new to turn it on.
FWIW we have seen where changing this value on some thinkpads also serves as reset for inaccurate battery status reporting
So, the usual caveat applies, proceed with exceptional caution