FWIW, I stumbled on an Indian solder manufacturer,
Saru Solder that makes 63/37 solder paste (no-clean, water soluble, and RMA flux variants, powder size = 4, and comes in jars).
Definitely worth checking out.
Otherwise, you'll be stuck gambling with
Mechanic brand paste from Aliexpress, Banggood, ... types of sources. It does seem to work based on user reports, but it could be old, stored under the worst possible conditions, and there's plenty of complaints about the amount being less than advertised. At least it's inexpensive.
In regard to powder sizes, there's a nice chart on wiki (
solder paste by size).
BTW, if you go into your profile and set your country, your nation's flag will be displayed beneath your userID. Makes it so much easier to help with links, particularly in regard to availability and cost to your location.