My questions about i2c

Can I connect multiple things into the same i2c pin?
If no, then how to get around that?
If yes, how to connect them?

Can I use the same modules on different boards if they have pins needed?

Can I connect multiple things into the same i2c pin?

YES

If yes, how to connect them?

by looking I2C up and getting more knowledge about it. Here is one random hit on a google search

Thanks. What about the 2nd question though? I think I can connect modules onto different arduinos, but I want to make sure.

I think I can connect modules onto different arduinos

you mean at the same time? or just if I2C modules are compatible with UNO, MEGA, ESP32, MKR, ...?

I meant compatibility.

yeah, I2C is I2C.

You might need to look at voltage levels (does it expect 3.3V or 5V or happy with both - there are I2C voltage adaptors / Logic Level Converter something like this) and double check pull-ups for your setup