embeddd linux getting started GPIO/I2C/SPI

Hi Community,
I have designed an add on board that is working well on raspberry using QT/C++.
I2C example: RTC ds3231 on PINs (3 SDA, 5 SCK)
SPI example: MCP2515 on PINs (19 MOSI, 21 MISO, 23SCK, 24 CS0, 22 INT)
GPIO example: output LED on Pin11, input from Optocoppler on PIN 13

Due to performance reasons I want to use UPboard (4GB/64GB) with ubuntu server and using the hardware from userspace.

Bios is updated to (https://downloads.up-community.org/download/up-board-uefi-bios-upc1dm15/), Hardware configured (Pin functions, GPIO directions, i2c speed)

ubuntu server is installed according WIKI (https://wiki.up-community.org/Ubuntu#Installation)

i2c-tools and can-utils are installed
modprobe can, can-dev,can-raw,mcp251x done
GPIO working well from userspace

and now there are the problems:

1. Problem: i2cdetect -y -r 1 does not detect 0x68 as expected
   no answer on all the other listed i2cdetect -l busses
   and no activity can be measured on the pins using an oscilloscope

2. Problem: ifconfig shows no can0
   I followed discussion (https://forum.up-community.org/discussion/96/canbus-hat-support)
   but where to put that last file and how to compile it in userspace (linux headers missing) ?
   as a try Kernel was compiled and installed but same results

I know that are embedded linux beginner questions but I do not know how to proceed
So any hint is very welcome, best regards!