Reply by myself:

Seems that I should use nvs_flash_secure_init() instead of nvs_flash_init() in order to initialize nvs in encrypted mode. However, the issue is that PlatformiO IDE doesn't support build flag CONFIG_NVS_ENCRYPTION and thus, the nvs_flash_secure_init() will just cause an error ...

I have an issue with nvs encryption.

The target is unicore esp32 (ESP32-U4WDH revision 3).

My project has the following partition structure:

# Name, Type, SubType, Offset, Size, Flags
nvs, data, nvs, 0x9000, 0x5000,
otadata, data, ota, 0xe000, 0x2000,
app0, app, ota_0, 0x10000, 0x140000,
app1 ...