The Microbrute e.g. offers a function to turn of automatic clock detection.
it's an option to disable automatics clock switch between internal and Midi. in Auto if a midi clk is received, it used it, if it disappears, it switch back to internal.
Both Mini and Micro does not average the received Midi clocks to determine the tempo(except some extrapolation for the LFO), they rather play an even (or not) on each received clocks.
That means that if you can provide an irregular midi clock that could to the job for the ARP.
how does the Minibrute react to irregular incoming clock signals?
on 1/4 it with play a note every 24 clocks, in 1/8 every 12, and 1/16 every 6.
So with swing = 1 at 1/4 step
clk 1 -> step 1 note on
clk 13-> step1 note off
clk 25 -> step 2 note on
clk 37- >step 2 note off
with different swing options note off will be postponed by few clock, one note over two
So if you're able to generate irregular midi clk messages, I think it could do the job.