Recommendations for good WiFi speakers

If you are willing to plug in each speaker into wall power you should audition the Rialto by Cabasse.  A simple pair only plugged into the wall for power, sound amazing and can fill a space larger than I imagined with excellent sound reproduction..  WiFi, Blue Tooth, Roon, Automatic Room adjustment with manual tweaking included.  Control from a speaker (tastefully discrete)  or from a cell phone.  

Yep. Rialto by Cabasse. Great suggestion. Thank you. 

But with the 4 grand price tag, that will have to wait until I hit the jackpot. 

Meanwhile, something more affordable will have to do for the second set of speakers. 

Soundcore Motion X600. Heard these while dining in a restaurant in Portugal. I was quite impressed by the sound quality. Great for a background music sound system.

…either battery-powered or can be pre-charged

I doubt you’ll find any that carries a self contained battery.  Most would be required to be plugged into an outlet such as the KEF LS50. I heard the Cabasse Rialto at audio shows twice and many commented they’re underpriced for the great clear and surprisingly satisfying low end.

After hearing the Vanatoo Transparent One here at AXPONA, I was very surprised how great they sounded at such an inexpensive price- I purchased a pair.  

Budget? It depends what’s out there. It’s the secondary set, kinda, so I don’t want to spend too much. 

That’s not an answer.  I’m not wasting my time playing your guessing game.  Good luck.