arm64 is the most widely used compilation target in the world, including a variant for Apple’s new processors. All smartphone toolchains, all mac toolchains, and most notably clang/llvm support it. It’s highly likely the CPU or SOC in any multieffect will either be ARM based or could be.
But yes, something would have to build it. The easiest would probably be to make it just be able to load plugins compiled for the mac.
Might be can’t get the heat away from the processor without the laptop fan jet engine spooling up for takeoff noise.
Might be the commercial side, there’s not enough projected incremental sales to make the project financials look good enough for the bean counters. I think that’s probably short-sighted if it’s what’s happening, but I’ve worked for a couple of market leading companies that were that way.
Running a linux kernel on an ARM SoC is something Android’s been doing for 15 years now?
True - but for VSTs on a small device manufaturers might choose as small/exotic RTOS instead of LINUX.
And how does that change the compiler toolchain, processor instruction sets, processor architecture executable formats, or binary ABI’s? Developing for embedded devices with custom OSes is still done on linux, Mac OS, and Windows; it just targets the embedded device instead of a desktop machine. That includes developing for iOS and Android, for that matter, but also for smaller embedded software, where sometimes there isn’t even an operating system at all. They still need binary ABI formats and processor architecture formats to target, and arm64 is the current common processor architecture for ARM processors. A small bootstrapping loader is written for the things that knows how to load the common format, in most cases.
If I were designing one of these things, I would really likely make it ARM based and target arm64. And these days most of these things are more capable than you think anyway; Korg’s latest three synths are all based on the Raspberry Pi, for example.
The NeuralDSP Quad Cortex we were discussing above, in fact, uses an ARM Cortex A5 running linux.
Now there are certainly other things to worry about, like targeting specific DSP coprocessors, but in general that thing is almost certainly using arm64 binaries.
You’d need to write a loader that dealt with loading the things, but you need to do that anyway, it’s just more complex. It (obviously) wouldn’t load arbitrary plugins from other manufacturers if they were doing any platform specific things in them (i.e. UI), which most of them will be, but when you are the plugin maker yourself, like NeuralDSP is, there’s a lot more freedom, and you could likely retarget your Mac plugins and remove anything mac specific when compiling for the embedded plugin host.
A lot of plugin development these days is done using cross platform plugin frameworks like JUCE, where you write the plugin core once and it targets compiling to all the binary formats (and plugin API formats) and supporting UIs on each system. So another option would just be to extend whatever plugin framework you used with platform support. Since the platform in question here is ARM Linux that’s probably not as big of a lift as it sounds.
The last time I was taking a look at doing this I was looking at JUCE and iplug2, both seemed pretty easy to use. Hmm, yet another hobby project to dust off 
Mod has a platform design that does exactly this concept except it’s not taking .vst. For some reason they opted to use another open development ecosystem.
So, we have a solution
Hardware VST hosts :
Cool, basically a headless Windows PC.
This is a hard one because all of these are very different sounding preamps.
The Ampeg Classic came out when Ampeg was not at the top of their game and has its own Ampeg like sound that doesn’t seem to match any other Ampeg product. I keep hoping they replace it with a small Rocket Bass preamp. I love those.
I would use a Behringer BDI-21 or a Caline Wine Cellar before getting an Ampeg Classic. The BDI and the Wine Cellar are both copies of the Tech 21 SansAmp BDDI.
The Sadowsky and the Aguilar DB 925 are very close in sound and have the same EQ points on their controls. The Sadowsky is supposed to be a little more HiFi sounding and has a volume knob. The DB 925 is smaller and cheaper.
The MXR Thump is a copy of the Echoplex preamp. It was the preamp used in an early delay system called the Echoplex. Either you love it, or you don’t.
I use a Tone Hammer into the front end of a Fender Rumble. The combination of the two makes me smile when I play.
If you like a traditional Ampeg sound, the Tech21 VT Bass DI was the darling of the bass world for quite a few years. They can be had second hand at pretty reasonable prices. It has a character knob that lets you change the overall sound from an SVT to a B15 Flip Top to a more modern sound.
Second favorite preamp I have owned, just fantastic.
