I don’t know the timeframe desired but I assume fast is desired, so I agree prior path looked real slow.
Disaster Recovery will suggest several methods. Restoring files if your Duplicati installation is lost is a Direct restore from backup files which still builds a database, but just for the latest version, so should move a little faster and might possibly avoid some problem only present in some older backup.
This temporary DB is not accessible for regular use, so is a poor way to go if one wants to continue to backup. I think one can get a permanent one-version database with --version on a repair command.
Your database recreating problem can of course be avoided if you can get the old one, or source files.
Duplicati.CommandLine.RecoveryTool.exe has no database, but does take steps to build its own index from the dblock files that it will download. Needed space is nearly the size now needed at destination.
I’m not sure how fast it runs on a big restore, and I’m not sure how well it handles a cross-platform one.
If it runs out of memory for this big backup, there appears to be a --build-index-with-files option.
Build RecoveryTool index in memory by default #4061
Somebody found it doesn’t restore empty files. That’s been fixed by gpatel-fr but is not in a release yet.
Further out are several tools that don’t use Duplicati code at all (so no need for .NET Framework, etc.).
Independent restore program is an older one in Python.
0-byte files are not restored with RecoveryTool #4884 mentioned a new variant of an older tool in Rust.
Rust Duplicati Restore and I have no experience with either Rust tool, nor do I know how they operate.