Yes, you can run NC20 on Raspberry Pi 4 with NextcloudPi.
Yes, Collabora is available for the Pi 4 via the appstore. Just has some installer issues being worked out.
Your best bet for Raspberry Pi is to use NextcloudPi, which is an official project designed to simplify installation and maintenance. Upgrading to version 20 is simply a matter of going to nc-update-nextcloud and typing 20.0.0 so there was no reason to stop using it. You can track status of testing new releases on their Github here. You can search the forum for more info on ncp and look at their category. They also have a Telegram channel at https://t.me/nextcloudpi
There is a lot of misinformation in this thread. Collabora is available now for arm64 devices, but there are some issues with the installer being resolved.
Collabora CODE is available from the appstore here for arm64 as of Nextcloud 19.
- You will need a 64-bit compatible Raspberry Pi to run it. 3b+ will not work because it has too little memory at only 1gb.
- You’ll need an absolute minimum of 2gb ram, but anyone with multiple users will need 4gb or more.
- Some installation issues are still being resolved regarding installation.
System requirements for Collabora CODE (in addition to Nextcloud itself)
Linux x86-64 or ARM64 (aarch64) platform
2 CPU cores
1 GB RAM + 100 MB RAM / user
100 kbit/s network bandwidth / user
350 MB space on disk
Nextcloud 19 with Collabora Online app 3.7.0 or higher
glibc (AppImage does not support musl libc)
Fontconfig (libfontconfig.so.1 - required by Collabora_Online.AppImage)
Hope this helps!