The biggest issue in film manufacture is the cost of keeping a coating line up and running. The capital expenditure requires high volume of coated film to be economical. Creating emulsion is comparatively easy (the big problems were sorted out long ago) and the rest is "just" marketing.
It is therefore common for film "manufacturers" to rent lines from other producers (which makes sense to them as well, as the lines date from earlier times and have capacity to spare, and the big enemy is digital).
As far as I know there are three major film coating lines still going in Europe:
- Ilford in the UK
- Inoviscoat in Germany (former AGFA line, does not have own brand)
- Foma in the Czech Republic
I am unsure whether to consider Ferrania as a film manufacturer or a performer of concept art. But they seem to have a line too.
Overseas Kodak has a line and Fuji have a line.
In Russia there is Tasma and in Ukraine Astrum but it is hard to verify if they are still in business of making new film, or just selling existing stock.
There is rumored to be a line running in China. Hindustani films in India are likely defunct by now.