No experience of a folding keyboard, my suggestion if you are keen would be to buy one on Amazon, be careful with the packaging, try it and return it if it is junk. I would not expect one to have arranger features.
The lightest digital piano with arranger features is the Casio PX S3100 @ 11.5kg, the less equipped CDP S360 @ 10.9kg.
The lightest 88 key keyboard is probably a Numa Compact @ 7.2kg, it does have a semi weighted keybed but no arranger features.
A Yamaha PSR E473 arranger has 61 keys and is 7.0kg, a better equipped X600 is 8.1kg and the X700 & X800 are 11.5kg
Ignoring arranger features a Korg Kross 2 has 61 keys and @ 3.8kg (3.8 is not a typo) it is the lightest and smallest keyboard out there, no onboard amp and speakers but I used to have one and had a Boss Katana Mini amp, both would also run on batteries.
As your 775 is 11.1 kg your options are very limited