tinyproxy socks proxy support was merged upstream.
https://github.com/tinyproxy/tinyproxy/pull/64#event-1460467771
Once it flows down to Debian, Qubes-Whonix should make use of it. Better than transparent proxying, better stream isolation.
Related:
add proxy capabiltiies (provides_network) to Whonix-Workstation / move Qubes updates proxy to Whonix-Workstation
T725