One of the unknown satellites at 435.800 MHz is BCCSAT-1 as the signal contains its callsign, from observation SatNOGS Network - Observation 3858224 checking the two signals that are visible in the audio waveform we have:
EDIT: Here are two other signals around 435.800 MHz:
One at ~435.805 MHz which is just a carrier:
https://network.satnogs.org/observations/3861511/
One at ~435.795 MHz which looks like dots:
https://network.satnogs.org/observations/3861451/
Wondering if any of these two belongs to STECCO transmitter or maybe to BCCSAT-1 too.
For completeness, we need to have in mind that we still missing reception of FEES and the two CANYVAL-C satellites.
EDIT2:
Signal at 435.795 MHz could be also BCCSAT-1, as in this observation SatNOGS Network - Observation 3861494 it is visible at this frequency.