I seem to recall others reporting success with Wiim devices recently. The clear advantage is that they are DLNA renderers so MC sees them directly without Bubble and that should be good news for the Android apps. Great to hear that it works gapless with MC; it would be nice if you further report your experiences. Wiim is on my list if I ever decide to abandon those $35 CCAs.
So far, I can report a few things. The $219 Wiim Pro Plus is well built. Unlike the Chromecast Audio, it uses RCA connectors, and the cables should stick in place. As you know, the CCA uses a 3.5mm headphone jack. My cats are always playing with the wiring and have often partially disconnected the cable, creating ground loops and noise in many of the ceilings, and it's is hard to track down which in the sea of CCA cables.
It also has an Ethernet port built-in, unlike the CCA. I didn't want to use Wifi for my CCAs given the number of units I have and multi-casting. So, I bought a $15 Ugreen OTG Gigabit Ethernet NIC for each of my CCAs. That makes each CCA a sort of spider, and extremely messy wiring, especially when you have multiple of them in one spot - I have two spots, each with 6 CCAs, and two 7.1 receivers, where each CCA is connected to the multi-channel inputs, either as L/R, SL/SR, or SBL/SBR. This is how I power all those zones inexpensively. This type of receiver (without any HDMI) is almost free for the taking on Craigslist if you look.
Anyway, I couldn't be happier about the way the hardware interfaces. There is also an analog input (stereo RCA) two digital outputs (coax and optical) and a trigger output, which would come in handy to power the receiver on/off, but that only works if you have a single zone.
There is a Chromecast audio built-in, so if you like the CCA, you can continue to use the Google cast feature. It's actually an optional feature. If you turn it on, you can't disable it later without a factory reset, which is rather silly. Most Android audio apps don't support DLNA, but many support Google cast, so it's probably best to keep the feature enabled.
Since I only have one WiiM, I couldn't test the native grouping support. I successfully grouped the built-in CCA with my native CCAs, though. That probably means there will be 2 sets of groups, one CCA group and one native group.
There is Alexa support, which I haven't tried, nor did I try the voice remote. I'm not an Alexa user, and not big on voice support in general.
On the downside, the advertised DSD512 support is not actually there (yet, hopefully ?).
WiiM has an app of its own that's not just for setting up the device, but also playing music from either local servers, or streaming services. I was able to browse my MC31 Media Server using the app. It is quite slow, though, with a 10-11 seconds delay when opening a large folder (Artists, Albums). No such delay when browsing with other apps (Bubble UPNP, JRemote2, MO 4Media). My server is hosted on an AMD 5700G, a completely silent box. Besides the slowness of the app, the Search feature does not work. So, be prepared to do a lot of scrolling if you use this app. However, if you manage to select your content in this app, it will play nicely and gaplessly.
I tried one music service with the Wiim Home app, Qobuz. It worked great. The search is instant. The playback is gapless. It even showed my previous playlist with the 400 Goldberg variations versions, which I had created with Roon. Speaking of which, I let my Roon trial expire. It is a very nice program and app, but I had a hard time accepting relinquishing manual control of my library. I was attracted to the gapless CCA support. But that was only for the Roon app. With WiiM, I'll get gapless in a bunch more apps/services.
As to how it sounds, I can't say that I am able to notice an obvious difference between it and the CCA. But I hooked it up to a zone with a lot of resonance (12ft ceiling, ceiling speakers more than 20ft apart). I played a few SACDs with DSD->PCM transcoding, and they sounded good.
Anyway, I only had the device for about 5 hours, those are just my first impressions.