Preliminary note: Assuming your pictures are already compressed (JPEG, PNG, WEBP,…), no matter what compression you use, there's not much that can be done, space-wise. There's simply no entropy to be reduced anymore. So, your whole scheme might fall flat here.
A usual method for this is using the Tape ARchive format (.tar). You can serialize a directory into a single TAR stream, pipe that through the internet (e.g. using SSH) and compress it on the target.
You also want to switch off SSH's built-in transport compression, otherwise it makes no sense at all to not compress at the sending host to begin with.
tar c Pictures/ | ssh -o "Compression=no" user@server "zstd -15 -T0 > Pictures.tar.zstd"
zstd -T0 (use as many CPU cores as you can get, for zstandard compression; the
-15 is the compression level; 15 is pretty brutal,
-3 is better than gzip but usually faster) with
xz -T0 (for parallel XZip compression) or
pigz (for parallel gzip compression) as you see fit. I do recommend zstd, it has a very good compression ratio / speed tradeoff;
xz is pretty slow, and gzip yields only very limited compression and isn't faster than zstd in comparably low compression settings.
Note, however, that encryption of your data probably needs more CPU than compression, so the question really is why you don't just
zstd -r --stdout Pictures/ | ssh -o "Compression=no" user@server "cat > Pictures.zst"