I get what you are saying. Unfortunately not the whole of the ROG is modular, especially with specific hardware such as charging, SD card etc. Not sure how this differs compared to the steam deck.

Me too, I came from a switch, I really enjoyed it but the move for me was for the bigger variety of games and the are more specials on steam, gog etc compared to Nintendo. But bear in mind that not all games are handheld friendly.

The ROG ally is extremely easy to repair and replace parts.

I understand the issues with Manjaro. But I am super excited with handhelds making a major come back. I think the next couple of years we are going to see major breakthroughs. Battery life is currently a big issue but this should be solved with more RND.

I currently play on Switch but I am getting very tempted to cross over to another device. But I will wait to see what Nintendo does next before I decide. A buddy of mine has the Asus ROG Ally which is also pretty impressive on its own.