Halion 6 vs Halion Sonic (SE) from developer’s point of view?

The difference between all three versions usually is explained for end users. But how about developers? If I want to sell a created library, which platform to choose? For example, Halion Sonic SE is free and it will give (potentially) more customers, as they don’t need to shell out money for the sampler just to give a try to a virtual instrument, but I don’t know if my library will be piracy-protected if it’s made and distributed for Halion Sonic SE. So what are advantages and disadvantages of producing the library for a particular version of Halion?

I haven’t seen a third party library other than for SE version. No point to limit potential users to owners of Halion Sonic or Halion 6.

Limitations of SE version are maximum of 2 layers and 4 effects on program bus. However you can have as many sublayers and layer busses with fx as you need. What you export from Halion 6 will become a single HSSE layer. You can have 2 of those in SE and I think 4 in Halion Sonic. In Halion 6 you can structure your program however you want.

As for copy protection they are all the same. If you join the Steinberg’s Halion partners program I believe they provide you with copy protection and the ability to sell through the online shop. But you need to contact them for more details.

Or you can come up with your own copy protection system. Have no idea how though.

You can still lock the macro page, layers and script modules on your own.

If I’m on Steinberg’s partners program, do you know how copy protection is realized for SE version? A user downloads it for free, buys an instrument as a .vstsound
file, loads it up - so at which step verification happens? Does SE
require entering any serial number pre-assigned to the .vstsound file by Steinberg?

Same way like with Cubase or Halion itself. You can download and install the vstsound but it will not run or even show up in mediabay until you activate the license in eLicenser.