I didn't know there's a procedure for it, I just compressed
blocks and
chainstate.
I see. In that case it's slightly different from
bootstrap.dat file since Bitcoin Core doesn't verify most things.
7z with LZMA2 algorithm could do better job, but i expect it'll be extremely slow.
Even if it saves a few GB, that's only a few percent anyway.
That's true. Last time i tried that with Bitcoin Signet, i got compression ratio 0.63 (505MB / 798MB). For comparison, compression you choose have ratio about 0.81 (397GB / ~486GB).