This is based in liquidx Board docs pdf
Use libuuu_1.4.43-32-geb273fb for legacy chips, obtained from pico-imx7_pico-pi_yocto-3.0-qt5_qca9377_lcd-800x480_20210429.zip. First, unzip the file. Then use mfgtool attached imx-mfg-uuu-tool-20210421.zip
Note: I dod not get any newer tool (1.5.x) working.