Leaving the WiiM app behind does not mean having to leave the WiiM behind.
I have a WiiM Pro.
I never, ever, use the WiiM app for music. It sucks. But, I have LMS which I natively point towards the WiiM Pro from my desktop (web browser), my iPad (web browser), or my Squeezebox Classic v3 (native interface). And I have an iPhone which I use for Apple Music / Amazon Music / etc., directing the output to the WiiM Pro using Airplay.
For me, the reason the WiiM Pro is such an amazing device is that I can use it as a network streamer
target without ever having to use its app. Instead, I use the native apps on the devices (LMS web interface, Apple Music, Amazon Music, etc.) that are most natural for me in the first place.
[Edit] I fully agree with @amper42 that those other systems (e.g., Audirvana, Moode, etc.) will provide a much better interface than the WiiM device. In my case, I'm already very happily in the LMS ecosystem. So a WiiM Pro tucked away in the back of my AV cabinet is absolutely fantastic (in my case). So for me, WiiM Pro (optical out) + my LMS + my iPhone is an unbeatable combination!!! For me, there is nothing else that is even remotely close to a WiiM Pro (now that Logitech abandoned their Squeezebox line). But, I would not choose the WiiM platform if their application was going to be the user interface to my music service. IMHO, it is a network target; not the music service.