I can open one and post pictures of the board if necessary.
I know it has just 4 MB of flash memory, but I think that with this type of low power device using just UCI con repurposed as smart switch, AP or as single task device.
“In a lot” suggests dump of used devices. The BT OpenHub, I am told, is a more suitable device, is already ported, and is available at around 5€ in singles
Pretty much, only if you port it yourself, or find someone excited to port an under-resourced device with a limited lifespan (32 MB of RAM is a significant problem).
Hard to justify the 20-100 hours to port a device in that class, especially when you can buy a new, supported, MTK7628-based, 8/64 device for $15 and 16/128 for $20 from a reputable manufacturer with support.
Given that there is no SOC support for RT63365E in OpenWrt or upstream linux and no drivers for the xDSL modem, it would take significantly more time than that. On top of that, 4 MB flash are already too tight for a plain wireless router, but xDSL firmware blobs tend to be rather large (in the multiple hundreds of KB range), there is no chance at all to fit into 4 MB flash (even if you don't install them, as there is no kernel driver anyways, the OEM partitioning will have reserved some space for the hardware).