If you have installed the resilio sync on your deck, then since the SteamOS v3.4 you probably encounter error when attempting to start it.

(deck@kutyma SteamDeck)$ /home/deck/bin/rslsync --config /home/deck/.config/resilio-sync.conf --nodaemon
/home/deck/bin/rslsync: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory
(127)(deck@kutyma SteamDeck)$ ldd /home/deck/bin/rslsync
linux-vdso.so.1 (0x00007ffd35076000)
libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007fd4d6ee8000)
libcrypt.so.1 => not found
librt.so.1 => /usr/lib/librt.so.1 (0x00007fd4d6ee3000)
libdl.so.2 => /usr/lib/libdl.so.2 (0x00007fd4d6ede000)
libm.so.6 => /usr/lib/libm.so.6 (0x00007fd4d6df6000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007fd4d5019000)
/lib64/ld-linux-x86-64.so.2 => /usr/lib64/ld-linux-x86-64.so.2 (0x00007fd4d6f0d000)

Don’t panick, at least not yet.

First things first, enable the write for the system:

sudo steamos-readonly disable

Then download the PGP keys:

sudo pacman-key --init
sudo pacman-key --populate

Should see something similar:

==> Appending keys from archlinux.gpg…
==> Appending keys from holo.gpg…
==> Locally signing trusted keys in keyring…
-> Locally signed 11 keys.
==> Importing owner trust values…
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: inserting ownertrust of 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
gpg: setting ownertrust to 4
==> Disabling revoked keys in keyring…
-> Disabled 53 keys.
==> Updating trust database…
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 11 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 11 signed: 96 trust: 0-, 0q, 0n, 11m, 0f, 0u
gpg: depth: 2 valid: 75 signed: 28 trust: 75-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2023-01-01

Then install the libxcrypt-compat package:

sudo pacman -S libxcrypt-compat
sudo steamos-readonly enable

Enjoy.