I made a minimal SAMD11 breakout for testing communication on the actual hardware. So far I just tested on some dev boards. If you haven't read anything about the SAMD11 so far. Let me give you a little taste of its specs: 16KB Flash, 4KB SRAM, 5-8 ADCs, DAC(!), RTC, up to 48MHz with external crystal, 12-22GPIO and 3 SERCOMs (UART, SPI, I2C for your choosing) and all that four about 1$ in single quantity. Apart from a load of legacy supported libraries, there is not much that speaks for the ATTiny85 anymore at this price point and size. If you wanna know more here is the datsheet.

Thanks to the wonderful work from mattairtech there is already a BOSSA compatible bootloader and Arduino core for the small and cheap ATSAMD11C14A which comes in a very easy to solder SOIC-14 package. Apart from a stable supply voltage the IC needs absolutely no other components to work, even when using USB it can use the internal clock sources!

My board only has a 3v3 LDO and a 10uF cap at the input and output of the LDO. Right now it even behaves great without a 0.1-1uF decoupling cap but I will definitely add one to the actual module designs. I just didn't have one rated for more than 24v in stock but nice to see it is able to work reliably with basically nothing. A true competitor to the ATtiny85. I'm hoping more people will adopt this wonderful MCU.

Blinky!

And yes USB works even if you don't give a shit about routing the traces anywhere close to each other or length matching them in any way. Its USB 1.x speeds after all, not terribly much to fuck up there.

(don't actually do that though, you should give at least a little care, I just knew that I will be ok in this case. Length matching +/-2.5mm will work out just fine at these low speeds, don't worry too much).