Assuming Termux is configured with ADB to connect to wireless debugging so adb shell works, get a static build of htop and make a script to deploy and use it:

mkdir -p ~/.local/bin
cd ~/.local/bin
wget https://files.serverless.industries/bin/htop.aarch64
cat > adb-htop <<EOF
#!/data/data/com.termux/files/usr/bin/bash
adb push $HOME/.local/bin/htop.aarch64 /data/local/tmp/htop
adb shell chmod +x /data/local/tmp/htop
adb push $PREFIX/share/terminfo /data/local/tmp/terminfo
adb shell -t TERMINFO=/data/local/tmp/terminfo /data/local/tmp/htop
EOF
chmod +x adb-htop

While this htop is a static binary with no dependencies, it still needs terminfo files, so our script copies them over into temporary storage (since adb shell can’t access files in Termux’s data folder).

Launch adb-htop to look into your phone:

If this is too much trouble, you can also use plain old in-built top with adb shell -t top: