I don't know about non-wax potted, but Artec do Firebird style mini humbuckers. The MVDA model has Alnico V magnets and comes in neck (MVDAN) and bridge (MVDAB) versions. https://www.ebay.co.uk/itm/ARTEC-MIN...-/202850496512

They also do a cheaper ceramic magnet version, but Alnico will be more vintage sounding.

I don't think you'll get non-potted pickups short of boutique suppliers as so few of this type of mini-humbucker pickup are made.

You could of course try taking a hairdryer to the pickup for a while and let the melted wax drop out. No guarantees of how 'un-potted' that would make it, but shouldn't do any damage if you only just get it hot enough to melt the wax. Don't use a hot air gun! But with a cover on, if that's loose and not stuck to the bobbin with wax, that can cause microphonics at quite low gain levels. So I'd turn the pickup upside down after heating so that any remaining wax falls between the bobbins and the cover.