How can I achieve level shifting from 3.3V to 0.8V and vice versa?

The following is a brief example.
For detailed selection methods, please use the following application notes.
→Tips for Selecting Level Shifters(Voltage Translation ICs) (PDF:2.62MB)

Step-down voltage conversion:
3.3V → 0.8V and other high-to-low voltage conversions can be achieved on the input side using input tolerance functionality. To meet the operating voltage requirement of 0.8V output on the low-voltage side, devices capable of operating at 0.8V must be used. Using a device that outputs more than 0.8V on the low-voltage side could potentially damage the 0.8V device. Toshiba recommends using level shifters (dual-supply type) guaranteed to operate from 0.8V. (Fig.1, Table-1）

Step-up voltage translation:
For voltage conversion from low voltages such as 0.8V to high voltages like 3.3V, the CMOS output of the preceding IC drives the CMOS input of the subsequent stage. Therefore, the high-level output voltage V_OH ≈ the power supply voltage V_CC. Voltage conversion is possible if the preceding stage's V_OH satisfies the high-level input voltage V_IH specification of the subsequent stage IC. Toshiba recommends using a level shifter (dual-supply type) as a product that satisfies the 0.8V V_OH requirement. (Fig.2、Table.1)