Is there a way to use exported snapshots in autocommit mode ?

Hello hackers,

Is there a way to use exported snapshots in autocommit mode ?

Either something similar to defaults
in default_transaction_deferrable, default_transaction_isolation,
default_transaction_read_only
Or something that could be set in the function's SET part.

Context: I am working on speeding up large table copy via parallelism using
pl/proxy SPLIT functionality and would like to have all the parallel
sub-copies run with the same snapshot.

Best Regards
Hannu