There are dozens of Raspberry Pi Alternatives and they all seem to have the same goal. Provide better performance than the Raspberry Pi. This just tells you that none of these boardmakers understand what Raspberry Pi foundation stands for.
Raspberry Pi are cheap
Have loads of documentation to learn.
Is supported by several Linux distros.
Free forums and Raspberry Pi Mag for information and projects.
The competitors like Khadas have none of these features. Looking at their website, they're very eager to sell their board and cost twice as much as Raspberry Pi. But when I try to search for learning resources or documentation, they fall short of provide anything useful. Khadas VIM4 is not supported by Ubuntu at the moment due to driver issues. I don't have these issues with Raspberry Pi.
SBC makers like Khadas, Radxa and Odroid are not into making Raspberry Pi Alternatives. Only the main stream press say they are. Big difference.
The markets are partially overlapping but are different. Looking into more details at the specifications show the differences. In the case of VIM4, true PCIe NVMe is a rather big difference. For instance if you want to do database at the edge. Same thing for SATAIII in for instance Odroid HC4 or M1. You can make nice NAS'es with them. Not so with USB drives. Etc.
SBC makers usually have a business market (e.g. signage, industrial, medical). They just happen to also sell to end users for additional revenues. But for most of them, their business customers are their main source of revenues. They don't care about Raspberry.