I love AV1 for compressing my movies to 720p. I also convert any audio to Opus. I get to archive a ton of content on peanuts. The videos look great on my PC monitor or my phone and they come in at around 452MB (1hr 24m video).

Here's my script if you're interested in trying it out on your content.

    param (
      [Parameter(Mandatory=$true)]
      [string]$sourceDir,
    
      [string]$destDir = $sourceDir
    )

    $ffmpegPath = 'C:\Users\sergi\Downloads\ffmpeg.exe' 

    Write-Output "Starting conversion..."

    Get-ChildItem $sourceDir -Include *.mp4,*.avi,*.mov,*.wmv,*.flv,*.webm,*.mkv -Recurse | ForEach-Object {

      $newFileName = $_.BaseName + '-av1-720p' + $_.Extension
      $destPath = Join-Path $_.Directory.FullName $newFileName

      Write-Output "Converting $($_.FullName) to 720p AV1..."

      & $ffmpegPath -i $_.FullName -vf scale=1280:720 -c:v libsvtav1 -crf 30 -preset 7 -c:a libopus -b:a 96k -ac 2 $destPath
  
    }  

    Write-Output "Conversion complete."

And I just invoke it against a folder to recursively convert stuff.

    .\av1-convert.ps1 -sourceDir 'D:\Movies to convert\'

As soon as there's something that can decode AV1 that's like an nvidia shield I will replace both of my shields. So far nothing like that exists to my knowledge. Even Roku 4k Pro's say "AV1" support in their spec but they still trigger transcoding on plex when doing a playback.