Forget the Dremel. For a flexible drive I have made an adaptor for the spindle end of the off-hand grinder, this takes a power drill type chuck, keyed or keyless, a cheap flexible drive from Axminster has a plain shank that fits in the chuck, and the other end, which comes with a hand-tightened chuck will also accept the same type of drill chuck., up to 3/8" capacity..
Plenty of power, but obviously limited to the fixed speed of the grinder.
My scrollsaw, a Delta of ancient lineage, has a thread in the end of the motor spindle specifically for a flexible, giving the advantage of two speeds, and the Axminster flexible end can be threaded down to fit this.
But I do also have two versions of a Dremel type, plus a small dental drill which is just like the device the nail bars use (and have one of those as well). These are only used on light delicate jobs. Variety is the spice etc.
Phil