Connecting an I2C device to a Raspberry pi Zero running OpenWRT 21.02.0

I'm running OpenWRT 21.02.0 with Kernel version 5.4.143 on a Raspberry Pi Zero v1.3. I'm now trying to attach an I2C display to it.

Currently, I2C 'seems' to run but devices are not recognized.

The display is connected to the RPi in the following way:

VCC -> 3V3
GND -> GND
SDA -> GPIO2
SCL -> GPIO3

I ran Raspberry OS on the RPi with the very same cabling and managed to connect the display successfully, so no hardware problems here.

Furthermore, I installed the following packages:

i2c-tools - 4.3-1
kmod-i2c-algo-bit - 5.4.143-1
kmod-i2c-algo-pcf - 5.4.143-1
kmod-i2c-bcm2835 - 5.4.143-1
kmod-i2c-core - 5.4.143-1
kmod-i2c-gpio - 5.4.143-1
kmod-i2c-mux - 5.4.143-1
libi2c - 4.3-1
python3-smbus - 4.3-1

The package kmod-i2c-gpio-custom, which is referred to in many documentation, is not available anymore according to this.
Then, I made the following additions to /boot/config.txt

...
# Place your custom settings here.
dtparam=i2c1=on
dtparam=spi=on

After a reboot, I2C on channel 1 seems to be up:

root@OpenWrt:~# i2cdetect -F 1
Functionalities implemented by /dev/i2c-1:
I2C                              yes
SMBus Quick Command              yes
SMBus Send Byte                  yes
SMBus Receive Byte               yes
SMBus Write Byte                 yes
SMBus Read Byte                  yes
SMBus Write Word                 yes
SMBus Read Word                  yes
SMBus Process Call               yes
SMBus Block Write                yes
SMBus Block Read                 no
SMBus Block Process Call         no
SMBus PEC                        yes
I2C Block Write                  yes
I2C Block Read                   yes

However, when I run i2cdetect -y 1 to discover all connected devices, the display does not show:

root@OpenWrt:~# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

When doing the same command on Raspberry OS, it would correctly show at position 0x3c.

This conforms to the output of dmesg:

root@OpenWrt:~# dmesg | grep i2c
[   11.130965] i2c /dev entries driver

Any idea what could be wrong here? The documentation on that topic is very sparse unfortunately.
Also kindly note that I am not an experienced kernel developer (not even an inexperienced one).

Thanks in advance