downloaded "bitcoin-26.0-arm-linux-gnueabihf.tar.gz" from bitcoin core website.
I assume you're talking about either bitcoincore.org or bitcoin.org. Anyway, that file is for 32-bit ARM, while Raspberry Pi 5 use 64-bit ARM (with support for 32-bit ARM software), so you better download 64-bit ARM version.
did the tar command, then ran the install "sudo install -m 0755 -o root -g root -t /home/user1/Downloads/bitcoin-26.0/bin/* " then the command above. should start qt for the first time? or did i miss a step?
It's wrong command. That command means you install Bitcoin Core on
/home/user1/Downloads/bitcoin-26.0/bin/*. Here's the full right command (i tested it on Debian),
$ tar xzf bitcoin-26.0-x86_64-linux-gnu.tar.gz
$ cd bitcoin-26.0
$ cd bin
$ sudo install -m 0755 -o root -g root -t /usr/local/bin *
$ which bitcoin-qt
/usr/local/bin/bitcoin-qt