As they say, be careful what you are wishing for, you might get it. My main motivation for making all those D1 Mini shields and selling them is to make this functionality available -- first from my @Tindie shop, and then, hopefully, from Aliexpress and eBay, as it gets cloned and manufactured cheaply.
Recently WeMos, the very company that makes the D1 Mini boards, has introduced a new product -- a 8x8 LED matrix shield similar to what I have been making here. Here's a link: https://www.aliexpress.com/store/product/Matrix-LED-Shield-V1-0-0-for-WEMOS-D1-mini/1331105_32812932291.html -- thanks to @davedarko for the tip!
However, this is not a clone of my shields. It's a complete re-make of the idea, with a different chip on board, using different pins and protocol for communication, and not software compatible. As far as I can tell there are not libraries or code examples for it.
I ordered one out of curiosity and will experiment with it, but for now let's see what I we can infer from the photos. The chip used is AIP1640, which seems to be a cheap clone of the TM1640 LED driver, produced by http://titanmec.com/. There seem to be no English datasheets for it, but there is one in Chinese available from http://titanmec.com/index.php/product/view/id/305/typeid/59.html
This chip can drive up to 8x16 LEDs, so only half the outputs are used for driving the 8x8 matrix -- you could drive a double or bi-color matrix with it (like this one: https://www.aliexpress.com/item/8x8-LED-Red-Green-Dual-Color-Dot-Matrix-Display-Module-TM1640-for-Arduino/32476051733.html). The inputs are connected to D1 Mini's MOSI and SCK pins through transistors, because it's a 5V device. The protocol it uses for communication is a weird mix of SPI and I²C: you send serial data, but because there is no chip-select pin, you denote start of transmission with I2Ć-like start condition. There are no addresses, though -- the device basically owns the pins it is connected to all the time. The driver does support PWM, but you can only change the brightness of the whole matrix, and not individual pixels.
There seems to be an Arduino library for the TM1638, that also supports TM1640, but it seems to be only for 7-segment displays. The library can be found here: https://github.com/rjbatista/tm1638-library
Speaking of the TM1638, I can't understand why they didn't use that chip, or one of the other LED driver chips manufactured by Titanmec (they have quite an interesting offer, see http://titanmec.com/index.php/product/lists/typeid/59.html). For instance the TM1629 or TM1638 (http://titanmec.com/index.php/product/view/id/303/typeid/59.html, English datasheet at https://retrocip.cz/files/tm1638.pdf) -- it's smaller, supports 8x8 LEDs and uses a proper SPI protocol that plays nice with other devices. Or use the venerable HT16K33, which is well tested, has proper I2C and already has a lot of existing libraries. I suspect they got a really good deal on those clones...
Perosnally, I find the TM1680 particularly interesting, as it should be capable of driving an RGB matrix with I2C: http://titanmec.com/index.php/product/view/id/393.html
In the mean time, I will keep selling my own matrix shields on Tindie -- they can't compete with these price-wise, but I think they are much easier to use, at least for now.