Currently, SOCKS5 proxy only supporting url like address:port.
Nevertheless, A SOCKS5 proxy is possible a UDS (Unix domain socket).

The tor and bitcoind are two examples of this usage:
a tor one-liner command "tor --SocksPort unix:/path/of/uds" will open a SOCKS5 proxy using UDS
a bitcoind one-liner command "bitcoind -proxy=unix:/path/of/uds"will connect to the above opened SOCKS5 proxy using UDS
Both tor and bitcoind can done this without error.

https://docs.deno.com/api/deno/~/Deno.Proxy
I tried to use UDS proxy on Deno 2.6.5 using { transport: 'unix'; path: '/path/of/uds'; }, then the tor deamon output: "(This port is not an HTTP proxy; did you want to use HTTPTunnelPort?)"

I also have tried to use SOCKS5 proxy on Deno 2.6.5 but it don't support "path" option.

I can only additionally open a HTTPTunnelPort or SocksPort using address:port on tor, then connect to it on Deno 2.6.5 using "url" option with HTTP/HTTPS or SOCKS5 proxy

There have two solutions to solve this problem:

Add UDS path support on SOCKS5 proxy
Add a new UDS option to allow users to choose using which method to connect the proxy (HTTP CONNECT method or SOCKS5 protocol method)