However, one can use the powerful scripting (Python or Java) API of Ghidra to import the files using a generic binary file format importer and afterwards modifying the result to create TEXT, DATA, BSS sections (in case of a program) or to set the address range correctly (in case of a TOS ROM).
You can find my scripts at https://github.com/czietz/ghidraScripts_for_Atari. Note that I'm fairly new to Ghidra and the scripts build on what I learned about its API in a few hours from the sample scripts and documentation. Most likely, I'm not doing everything the optimal way.
