I tried a swiss micro. Small, rpn... Awful awful to use.
When my hp34 died i was sad to see that there were no good calculators to be had. Theres times i wanna calculate while not sitting at a computer, and phone sucks because no buttons.
Luckily i found this while it was still active.
34s:repurposing_project [HP Calculator Wiki]
i managed to get a cable and ordered 10 hp30 off ebay for $5 each, made a bunch of wp34s and gave most away as gifts.
Its not rpl but has terrific features, especially random numbers and base conversion.
Try the phone app.