CC1101: Impossible to send a long preamble about flipperzero-firmware HOT 2 OPEN

I've already mentioned our position on packet mode here: #3758 (comment)

I think easiest way for you will be to extend cc1101 driver that we have in lib/drivers with functions you need and use it directly in your code completely bypassing furi_hal_subghz.

from flipperzero-firmware.

no, you're wrong. if you read the datasheet on the CC1101, it clearly says that packet mode transmission begins (like any other) after the STX strobe is issued. this is done by sending the command
subghz_devices_set_tx(device); after the data to be transferred has been loaded into FIfo

also your code will not work without the correct preset created specifically for your task
even in your example it is there
https://github.com/atc1441/E-Paper_Pricetags/blob/5ac32ec28b03c9265a9b34ad54de8daa79a5f21b/Custom_PriceTag_AccesPoint/ESP32_Async_PlatformIO/RFV3/cc1101.cpp#L53

After correct preset configuration and timely loading of new data into Fifo, it is possible to perform streaming of any length

from flipperzero-firmware.