The LoongArch ISA is used on CPUs created by Loongson, who have internally created a loongarch64 port that they have turned into an unofficial Debian port called loong64.
Porterbox
There are currently no porter boxes available. However, you can set up your own loong64 sbuild chroot with LoongArch/sbuildQEMU
References
Status: unofficial loong64 port accepted
Discussions: <c32d3af9f9ebc362431e2f208f75b52ba64779c0.camel@physik.fu-berlin.de> <b5a53692-592c-2e3d-a996-a8d6692f4eb1@loongson.cn> <12133b5.b049.182493b9628.Coremail.sangmeng@loongson.cn> <Y0FqIwOJuBMGGHxZ@thunder.hadrons.org> <OS0P286MB0641F6E5B9C3AE7434E9638ACD369@OS0P286MB0641.JPNP286.PROD.OUTLOOK.COM> <37f3f5f2.5495.18432e942d7.Coremail.sangmeng@loongson.cn><1bcbfd39.6450.1843d9f7e2c.Coremail.zhangdandan@loongson.cn>
Mailing list request: 989125
IRC channels: #debian-loongarch, #debian-bootstrap, #debian-ports on OFTC
Documentation: https://loongson.github.io/LoongArch-Documentation/
Unofficial FAQ: https://blog.xen0n.name/en/posts/tinkering/loongarch-faq/