I typically play what I'm calling my "rhythm stage setup", though it needs a better name. It's a keyboard, foot drums, breath controller, and whistle-controlled synthesizer, connected with code I write, that lets me give a full and varied sound while keeping the control and flexibility to still be live. Here's what the pieces look like laid out on the floor:

They are:

1. Four Yamaha KU-100 beaterless kick drum pedals. I play with two under each foot, one for the heel and one for the toe.
2. A Yamaha DTX 500 electronic drum kit brain. This turns the signals from the kick pedals into audio (for the hall) and MIDI (for triggering downstream instruments).
3. An ugly mess of TRS cables that connect the pedals to the brain. I wish I had something nicer, but I'm not sure anyone makes a simple cheap reliable 6ft 4x TRS snake?
4. A USB keyboard, which I use to switch modes on the system. A cheap and simple way to get a ton of buttons. I've taped over many of the keys with labels so I remember what I've made each key do. I do wish I had lights or some other way to see what they current mode is, other than remembering what buttons I've pressed since I last fully reset it.
5. Two powered USB hubs. I want to plug more things into the two Raspberry PIs that are the core of the system, some of which draw more power than a PI supplies, and I also need to power the PIs.
6. Two power adapters, one for each USB hub.
7. Two Raspberry PI 3B computers in simple cases. Pre-pandemic they were cheap, and I think they're finally back to being cheap again? They're configured exactly alike, and they choose what role to take on based on what they find plugged into them on bootup. This means if one breaks I can swap the other in, since one of them is much more critical to what I'm doing than the other.
8. Spare SD cards, and a card reader adapter. The SD cards get corrupted more often than I'd like, so it's good to have spares.
9. USB-to-MIDI for the drums.
10. USB-to-MIDI for the keyboard. When I'm using someone else's newer keyboard with USB midi I bring an A-to-B cable instead.
11. Power adapter for the drums.
12. Keypad to control the whistle synthesizer. No need for a full keyboard since this has many fewer settings.
13. Cheap XLR A/B splitter so I can send a single mic to either the whistle synth or directly to the board (when using the talkbox on mandolin).
14. USB A to micro B and A to USB-3 micro B cables for one of the computers: the former to power the computer from the hub, and the latter to connect them over data.
15. The same, for the other computer.
16. XLR to TRS adapter for the whistle synth's audio interface.
17. Focusrite 2i2, the whistle synth's audio interface. I needed something that could take a dynamic mic input.
18. Breath controller. Let's me use how hard I'm currently blowing to add expression to my playing.
19. Cheap little USB audio interface (and a spare), with a 3.5mm trs to dual 1/4 TS adapter. This is for the other computer. Good enough for live work!
20. Microphone to pick up my whistling to control the synth.
21. XLR cable and mic clip for that microphone.
22. Two two-channel DI boxes: keyboard, drums, computer, and mandolin.
23. USB C to USB A cable to connect to, and power, the Focusrite. I do wish it had been designed with separate cables for these, so I could use one fewer hub.

I usually also have a bunch of quarter inch cables, a few more XLRs, a couple power strips, a yoga mat to keep things from sliding around on stage, a booster seat so I'm the right height to play, and often additional spares.

Note that this doesn't include the mandolin aspect of my setup, since that's much more standard: just a series of guitar pedals.

Here's what it looks like packed to go to Friday's gig in CT:

When I fly I wrap everything in my clothes and, along with my mandolin pedals, it comes in at just under 50lb in a full-size checked bag.