Fein multimaster: I have one of these which may or may not be quite what you're after, but is a fantastically useful tool, both as a sander, and as a precision saw for trimming and and such. Fein invented this design, but other makes now exist, but it's worth noting that Fein is a top notch brand. They also do their bigger model : Supercut, but I've never found the standard model lacking.l so didn't pay the extra (And I'm a tool snob). As well as delta/triangle sanding pads you can get tiny finger pads and a (to be fair not great) profile sander thingy.
Worth mentioning that in sanding mode it runs much much faster than a standard palm or delta sander, but with a tiny orbit
I've not owned a dremel, (nor a proxxon perhaps a higher end equivalent), but have heard mixed opinions. Foredom is another model with a separate motor and flex drive shaft which is the standard professional item for jewellers and the like but never used that either
https://www.axminstertools.com/fein-mm500-plus-top-multimaster-230v-10781
Anyhow, the Fein above is one of my most used and useful power tools and one I would bot want to be without. There are also battery versions, but I've always gone for mains for sanders as you are likely to use them for an extended time