Crazy as a Left Handed Computer

We had a subscription for this service for £2.99 a month and that was acceptable for what is a limited concert and documentary music streaming service, but the price has been increased by more than 25% to £3.99 a month. For this service a price exceeding the original subscription amount is way too much, so we have cancelled the renewal of our subscription. The Qello streaming music concert and documentary service isn't recommended at that price. YouTube offers better concerts free of change!

Kind of disappointing that you can only have 2 devices streaming at one time per account.

Tidal isnt part of their streaming service...so "NO"
but you could use the box as a client/server streamer, so the 2nd question is YES.
You can probably find posts on using sonos or other by searching.