Two gotchas...
The ancient 'Baghdad Battery', which was probably used to plate or otherwise 'improve' jewellery. Former is less likely as, IIRC, both the Voltage and Amperage are inadequate. Latter would mimic the Incas' trick of starting with a low-carat, mostly copper alloy, leach in acid spring, rinse, polish, repeat until the surface is pure 24 carat. Literally, turning 'Base Metal' into gold.
If not the legendary 'Philosopher's Stone', then a fair facsimile...
Electrostatics. You can generate enough for fun tricks by rubbing fur on amber or glass, by dripping water, by a dozen variants of rotating devices. But, like the Alexandrian steam-spinner, it is nigh impossible to get useful work from such...
One way to keep electricity off the map is to have the Antikythera Device reach port. IIRC, this wasn't a one-off, there may have been one in each of a dozen Greek cities. But, they seem to have gone to scrap due looting...
Have the Romans take up clockwork enthusiastically ??