Some of the niche features of this thing are still beyond me, but I think now that I have a reference spectrum analyzer, a DIY logic probe, a DIY differential probe and an active probe, I can finally dare to say a few things about this scope.
The sweep generator in this case is a Chinese ADF4351 board ( https://www.banggood.com/35M-4_4GHz-PLL-RF-Signal-Source-Frequency-Synthesizer-ADF4351-Development-Board-p-1129041.html ) controlled by python script via STM32 board. This is by far the cheapest microwave signal source up to 4.4 GHz
Also here's another SLA print with an M5 fastener

Leonid Nemiro
2018-09-15 00:30:06 +0000 UTC