Multiple app catalog relays are already supported in the new app.
The UI is missing so we'll call it an Easter Egg for now, but if you publish a 10067 event to Purplepages (or Zapstore relay) and restart it will pick it up.
nak req -k 10067 -l 1 purplepag.es
Relays must be app catalogs. The only one I'm aware for now is relay.zapstore.dev, the default.
Stay tuned, management UI and more compatible relays coming soon.
GM!