My team is working on this problem in the context of creating Node.js single-executable applications. While the naive approach of just appending data at the end

My team is working on this problem in the context of creating Node.js single-executable applications. While the naive approach of just appending data at the end of the binary works, it is not friendly with code-signature in macOS and Windows given that signing operates on PE and Mach-O sections. We have recently open-sourced a small tool called Postject (https://github.com/postmanlabs/postject https://github.com/postmanlabs/postject), which is able to inject arbitrary data as proper ELF/Mach-O/PE sections for all major operating systems (with AIX support coming). The tool also provides C/C++ cross-platform headers for easily traversing the final binary and introspect whether the segment is present or not. The tool is based on the LIEF (https://github.com/lief-project/LIEF https://github.com/lief-project/LIEF) project. At Postman, we are making use of this on our custom Node.js single-executable applications and soon on our custom Electron.js builds too.