I have too many different camera systems but enjoy flitting from make to make or different cameras within a make. Consequently I standardised on the Hama DCCS remote trigger system. Whilst no longer made, components seem to be fairly easily found, with the exception of a rare later model Sony adapter. My SL2 and I presume, all the SL series, has a remote shutter socket which has the same pin configuration as Panasonic. I have the Hama wired trigger, the wired intervalometer and the wireless remote, each of which would be fitted with the relevant manufacturers adapter to plug into the camera.
The wired remote works just fine for half and full presses. I haven't tried the intervalometer but suspect it would work without issues. The wireless transmitter communicates with the receiver, in turn that is attached to the applicable adapter. I have used my wireless trigger/receiver with Nikon/Canon/Olympus/Fuji and Panasonic cameras with no issues. It will not work with the SL2.
The camera clearly knows something is going on as regards wireless activity and does not permit the shutter to fire in this state. So, as a cheap off brand system the wired arrangement works well especially for those who also run different systems. If anybody knows of another off brand wireless trigger system that will work on the SL2, please do comment.
Next up for investigation is try out my Godox X3(L) flash trigger with a pair of Godox TT865 flashes I already owned. From what I've read, these flashes will support cross brand activity for both manual and TTL flashes, except when using a Leica camera, that will be manual only. Only more recent Godox flashes will support Leica TTL as well, such as the V100 and AD200 Pro, so a voyage of discovery awaits.