EEGLAB supports reading most iEEG data formats (EDF, MEF3) through native code or plugins. The BIDS-matlab-tools EEGLAB plugin also support importing BIDS formatted MEG data. You may install plugins from the EEGLAB plugin manager (menu item File > Manage EEGLAB extensions).
For example, after installing the MEF3 and BIDS-matlab-tools plugins, you may import the ds003708 BIDS dataset. First, download the data. Second, use menu item File > BIDS Tools > Import BIDS folder to STUDY. Leave all defaults and press OK (you may also select the column of interest for event types). Alternatively, use menu item File > Import data > Using EEGLAB functions and plugins > Import MEF3 folder to import the mefd folder located in the ds003708/sub-01/ses-ieeg01/ieeg/ folder of the BIDS dataset.
When importing with BIDS, the advantage is that, along with the data, you will likely have access the iEEG electrode locations and relevant events. We show below the raw sEEG data for the unique subject in BIDS dataset ds003708.
Below the channel locations for the same dataset above are shown.
Even if you are not planning to use EEGLAB to process iEEG data, importing your iEEG data into EEGLAB and resaving it into an EEGLAB dataset may be useful to process it in other software.
Other relevant resources for processing iEEG data: