I found this article very interesting:
An extract:
The sound box device — first introduced by India’s largest fintech company, Paytm, in 2019 — has been a runaway hit among small Indian businesses. Neighborhood mom-and-pop stores (kiranas ) and street vendors, who had traditionally shied away from paying for tech services, have warmed up to the sound box.
The smart device — essentially a speaker bearing the logo of the fintech company facilitating the transactions — comes with a built-in SIM card. Most sound boxes can read out payment confirmation messages in English and multiple Indian languages, such as Hindi, Tamil, Telugu, Bengali, and Punjabi.
In Indian cities and towns, sound boxes can now be seen across diverse businesses — from kiranas and clothing stores to produce carts and shops selling smoking products.
A Paytm spokesperson told Rest of World that in the third quarter of the 2023 financial year, the company’s gross revenue from Paytm Soundbox subscriptions touched 1,197 crore rupees ($150 million). The company has 6.8 million devices deployed across the country. The spokesperson said Paytm has tied up with a domestic manufacturer to produce both the hardware and software for its sound box.
The success of Paytm’s sound box has prompted other fintech companies to launch their own versions. BharatPe was the first to rival Paytm in the segment — it launched its sound box, BharatPe Speaker, in June 2022. PhonePe followed suit with Smart Speaker a couple of months later — the company has so far deployed 2.2 million devices in India, a spokesperson told Rest of World.
GooglePay joined the race earlier this year, piloting its Soundpod sound box in the country’s kirana stores. Several Indian banks, such as IndusInd Bank and AU Small Finance Bank, have also launched similar devices, hoping to cash in on the growing popularity of sound boxes.
I love to hear stories like this; where an unexpected piece of UX solves a big problem and can turn into a business initiative all of it’s own.
Although it’s probably too late to capitalise on this rush, I’m sure integration of audio into the Z Go! application (or any other Zcash wallet) would be a nice addition for people around the world who face this issue…
I can hear it now. 
Check the “Kiosk mode” and “Audio notifications” checkboxes on the settings of a future Nighthawk Wallet build and hear “Incoming payment of 0.2 ZEC received” so the seller doesn’t have to keep an eye on their device as they serve their next customer.