try @testing-repo 2

applications/podman.sls

@@ -6,7 +6,14 @@ applications_podman_pkgs:
     - pkgs:
       - podman
       - podman-openrc
-      - "podman-compose@testing"
+
+application_podman_compose_pkg:
+  pkg.installed:
+    - pkgs:
+      - podman-compose
+    - fromrepo: https://dl-cdn.alpinelinux.org/alpine/edge/testing
+    - require:
+      - applications_podman_pkgs
 
 applications_podman_rootless_confd:
   file.keyvalue: