Can somebody recommend a layout for a programmer for a 54 key kyeboard?

Take a look at ZSAs oryx configurator for Voyager (52 keys) - you'll see some general configs and development ones etc.

In general, for my moonlander I would have the first layer with all the normal alpha numerics and a few symbols like <>?

But the second layer would contain most symbols, arranged/grouped in a manner which was natural for programming - e.g. grouping keys together like (), [], {},