How compatible are the new Subor consoles with HDMI?

[maxellnormalbias]

I saw a Little Tyrant / Subor console with HDMI for sale at a market near me and I wondered how compatible they are? Do they have inaccurate audio emulation? (I'm thinking of the duty cycle issue) Do they scale well?

I'm assuming that, if they support HDMI natively, they're using a new NES-on-a-chip implementation (maybe pirated from Kevtris' HDL) or some kind of FPGA. They could just be attaching a commercial composite-to-HDMI converter on the inside, which wouldn't surprise me.

I'm wondering because it looks half-decent it might be a low-effort and cheap way to get old games on my flatscreen TV without buying framemeisters and stuff.