One such option is FTP (File Transfer Protocol), where you could take the mod folder and install mods to your SD card over your internet formatted for the SaltySD mod injector (you would just need a FTP server on the Switch, like sys-ftpd).
Alternatively, it can save the compressed files to any path available from your computer (for instance, the SD card, if it's inserted), or inject them directly into another Arc.
For an example mod folder, consider:
| +-> param/
| +-> fighter_param.prc
The program runs through the .NET Core runtime (dotnet.exe), if you don't have it you can download it from the link in the requirements. To run the program and see the help text (which explains how to use it), open a command line and use `dotnet ArcInstaller.dll -h`. For help please refer to people in the SSBU modding discord; for bugs or issues, let me know there (@Arthur) or on the Github issues page