good SMPS for car or off-grid use?

Looking at options to power Purifi modules and a homegrown class AB tweeter channel not using the Hypex SMPS1200. Since I have a couple of solar modules, a charger and a battery to play with, I wondered why not go from 12 or 24 V.

While car audio amps have been using SMPS for ages, the only design I found on the web was this, with quite good performance, apparently:
Switchmode Power Supply For Car Audio

However, the article is nearly 20 years old. I was wondering if there aren't better controllers around to use today, better in terms of:
- noise
- efficiency
- maybe even coming with integrated MOSFETs?

Is anyone aware of commercial products or, preferably, diy projects, e.g. here on diyaudio?

Is that controller still up to date? What kind of ferrite core is recommended from what can be sourced in Europe?