just found this thread and a tear of happiness fell! The first round of drinks or whatever you fancy @meisterlone if Im ever in your area for just this so far. bravo!
This thread is amazing, fun to read the process of this device being cracked open.
I ended up finding one of these in a gutter, this thread is a good excuse to mess around with it 
I got as far as running open.sh, and heeding the warning, the U-Boot binary is unrecognized: https://share.riseup.net/#fXCGeHBQdZbJ981idC-oEw
I'll spend some time looking into this, but are there any pointers?
Immediately, the U-Boot build is about a year newer:
600607 0x92A1F U-Boot version string, "U-Boot 1.5.1 [spf11.4_csu2] (Jun 15 2022 - 09:05:59 +0000)"
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
0 0x0 ELF, 32-bit LSB shared object, ARM, version 1 (SYSV)
4552 0x11C8 Certificate in DER format (x509 v3), header length: 4, sequence length: 1223
5779 0x1693 Certificate in DER format (x509 v3), header length: 4, sequence length: 1035
6818 0x1AA2 Certificate in DER format (x509 v3), header length: 4, sequence length: 1000
235252 0x396F4 uImage header, header size: 64 bytes, header CRC: 0x22DE964A, created: 2019-05-17 11:08:58, image size: 1910412874 bytes, Data Address: 0x8CDE964A, Entry Point: 0xFA21974A, data CRC: 0xC97E974A, image name: ""
469524 0x72A14 SHA256 hash constants, little endian
507108 0x7BCE4 CRC32 polynomial table, little endian
508132 0x7C0E4 CRC32 polynomial table, little endian
600607 0x92A1F U-Boot version string, "U-Boot 1.5.1 [spf11.4_csu2] (Jun 15 2022 - 09:05:59 +0000)"
610976 0x952A0 Flattened device tree, size: 3378 bytes, version: 17
614368 0x95FE0 Flattened device tree, size: 3509 bytes, version: 17
617888 0x96DA0 Flattened device tree, size: 3509 bytes, version: 17
621408 0x97B60 Flattened device tree, size: 3509 bytes, version: 17
624928 0x98920 Flattened device tree, size: 3509 bytes, version: 17
628448 0x996E0 Flattened device tree, size: 3509 bytes, version: 17
631968 0x9A4A0 Flattened device tree, size: 3509 bytes, version: 17
635488 0x9B260 Flattened device tree, size: 3509 bytes, version: 17
0 0x0 ELF, 32-bit LSB shared object, ARM, version 1 (SYSV)
4552 0x11C8 Certificate in DER format (x509 v3), header length: 4, sequence length: 1223
5779 0x1693 Certificate in DER format (x509 v3), header length: 4, sequence length: 1035
6818 0x1AA2 Certificate in DER format (x509 v3), header length: 4, sequence length: 1000
235252 0x396F4 uImage header, header size: 64 bytes, header CRC: 0x22DE964A, created: 2019-05-17 11:08:58, image size: 1910412874 bytes, Data Address: 0x8CDE964A, Entry Point: 0xFA21974A, data CRC: 0xC97E974A, image name: ""
469524 0x72A14 SHA256 hash constants, little endian
507108 0x7BCE4 CRC32 polynomial table, little endian
508132 0x7C0E4 CRC32 polynomial table, little endian
600607 0x92A1F U-Boot version string, "U-Boot 1.5.1 [spf11.4_csu2] (Jun 15 2022 - 09:05:59 +0000)"
610976 0x952A0 Flattened device tree, size: 3378 bytes, version: 17
614368 0x95FE0 Flattened device tree, size: 3509 bytes, version: 17
617888 0x96DA0 Flattened device tree, size: 3509 bytes, version: 17
621408 0x97B60 Flattened device tree, size: 3509 bytes, version: 17
624928 0x98920 Flattened device tree, size: 3509 bytes, version: 17
628448 0x996E0 Flattened device tree, size: 3509 bytes, version: 17
631968 0x9A4A0 Flattened device tree, size: 3509 bytes, version: 17
635488 0x9B260 Flattened device tree, size: 3509 bytes, version: 17
Ack, missed file hosting constraints. Pushed to a repo: https://git.sr.ht/~jleightcap/sax1v1k-openwrt/blob/main/uboot-partition.img.tar.gz