I guess it depends what you mean by "custom watch faces" but I've got 12[1] things that show different variations of clocks and widgets installed on my Watch and the Watch app offers a few more[2].
[1] Activity Digital, Solar Graph, Modular, Infograph, Modular Compact, Liquid Metal, Solar Dial, Unity Lights, Gradient, Pride Woven, World Time, Pride Threads.
[1] Activity Digital, Solar Graph, Modular, Infograph, Modular Compact, Liquid Metal, Solar Dial, Unity Lights, Gradient, Pride Woven, World Time, Pride Threads.
[2] https://imgur.com/a/A9u4EYr