Unfortunately it's not a big list.
The operators which only have turbines are extremely unlikely to be able to give you a start with a bare float endorsement - for a gig in an amphib caravan most operators will be looking for around 500 hours of float experience.
With floats it is very much is a case of being in the right place at the right time with the right attitude. The last time the company I work for advertised there were about a hundred applicants, some of which had thousands of hours of float experience (and others that didn't even have a float endorsement
).
In our case the minimum requirements vary depending on the level of experience of the pilots in the company at the time we're looking for another pilot. Sometimes a bare endorsement is enough to get a start, at other times significant experience is required. Historically most of those that got a start with a bare endorsement actually moved up with no offer of employment, found other work - and waited, and kept in touch by calling in regularly. On the same token there have been others that moved up and didn't get a start either.