Peter Gamma from www.petergamma.org is highly interested in SBCs in the zero size. The most used is as far was we know currently the Raspberry Pi zero 2 w. For this device DietPi is recommended because of the only 512 MB RAM:

Before you become a DietPi developer, since your Raspberry Pi zero 2 w has only 512 MB RAM try the Orange Pi zero 2 with with armbian

DietPi is not for everyone, it has no desktop. Therefore it would be highly desirable to have an alternative. Three years ago, ETA PRIME introduced the Radxa Zero as a Raspberry Pi Zero Killer:

But it was not. It was powerful. But even the Raxda Zero 2 was mainly a SBC for gamers, as the YouTube video maker Micro Linux has shown:

Micro Linux Radxa zero 2 demos – a device for gamers?

We did not find any demos which would show that the Raxda zero (2) it is a device which would fit for our applications. The Radxa zero 3 w is better now. Radxa is a company located in China:

https://radxa.com/about/#contact

Radxa has a forum which is great:

https://forum.radxa.com/latest

Here is a YouTube review of the Radxa ZERO 3W by Platima Tinkers, an excellent SBC reviewer from Australia:

Pros: (according to the Platima Tinker)

• it has usb-c 3.0 (the Orange Pi zero 2 has only usb 2)
• it boots fast, faster as the Orange Pi zero 2 w

Cons:

• How long is Radxa on the market?
• We do not know much about Radxa
• In the example of the Mango Pi quad, a SBC in which we where also intested already disappeared from the market.
• This shows how quickly SBCs disappear from the marked, even if they have good ratings.
• How is this with Raxda?
• A company name which causes me often problems to type the name correctly.
• I had the same problems with typing «MangoPi MQ-Quad» by MangoPi.
• In contrast, Orange P’s are on the market since many years.
• There SBC names are easier to type.
• But it is not not so easy to see through the model stragedy of Orange, if there is one.
• We did not find many offers on Aliexpress and eBay for the Radxa Zero 3 w.
• Orange for comparison has a big variety of offers for instance on eBay and Aliexpress.
• We suppose there are lesser issues with availability with Orange SBCs than with Radxa SBCs.
• Orange is on the market for a longer period and availability was stable even during Corona.
• We do not know much about the availability of Radxa SBCs.
• We are looking for a SBC for mobile use.
• We suggest to use only passive cooling for mobile use.
• Active coolers draw a lot of power.
• Therefore we prefer a SBC which draws little power, these are for instance the Raspberry Pi Zero 2 w or the Orange Pi zero 2 w.
• The Raxda zero 2 w has a very slow wifi.

According to the video review of Platima Tinkers the hardware of the Raxda Zero 2 w is good, but the software and documentation are in a stage which costed him a lot of time. But he says it is still much better than the Rasbperry Pi zero. Software and documentation are not recommended by Platima Tinkers.