Thank you very much for sharing this!
I had practiced with Decker for a little while but was not aware there was a limit to the length of sound clips. I'll see if I can compose in the chiptune player you created, which I must say is very impressive!
i love millie's janky sequencer and jankytunes!!!!! im its #1 fan. lmk if you have any q's about working w/in its limitations though i gotta say that i am a silly little ghost who just does everything by instinct and have no theoretical knowledge. but! i (extreme perfectionist) am content with the tunes i've created in millie's sequencer and can guide to the best of my ability if you need or want feedback. of course if you're confident in yourself pls just take care n have fun!! (sorry if its overstepping to offer help)
A few tips on using JankyTunes
The contraption I linked is what you'll use for getting things playing in your deck, but for composing it you'll want to use Janky Sequencer, which gives a nice(ish) interface for entering in notes and such. If you want to tweak the default sounds, they're all adjustable under the Synth Parameters button, but if you're trying to test and try out sounds, then my Janky Synthesizer deck uses the same synthesis technique underneath so it can be a good place to test and refine sounds.
Also since the format it saves is just CSV files, I sometimes find it easiest to just edit them in Excel, where it's easier to copy and paste segments and such.
Hope this helps. I am also happy to answer questions if you can't figure this out.