I suspect the serial decoders are now officially supported in the latest firmware revisions - this is the word of an owner; I don't have one. However, just beware that the same owner reported this function limits its storage memory to 1% of its capacity (from 10M to 100k points only).*
For the ones that are ok with the USB oscilloscopes, one alternative is the relatively inexpensive Owon VDS1022 - a two channel 25MHz USB oscilloscope that can be had for less than 100 dollars (US) and, although it does not have stellar specifications, it works well to look at analog signals and its software is well made and a version is being maintained by some other users in this forum.
https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/400/*For the folks that do not understand the storage function for data decoding: think of it as a measure of how many bits the master device sent to the slave device and the oscilloscope could capture and be able to "translate it" (decode) to show in the screen. Depending on its size and the rate to which the oscilloscooe is capturing the data, the storage memory can be filled too quickly to grab any meaningful exchange between the two devices or too large so the information is lost in a very large stream. This is oversimplified, but hopefully it gives some idea.