..going smaller and you are entering wasp fart in a tin can sound quality...

There are plenty of cheap n cheerful plastic micro amps..

there's this on Amazon for 15 quid
GuitarAC Portable Battery Powered Mini Amp for Electric Guitar

The better known 'quality' brands are around £30 - £40

maybe google youtube demos to check if any can manage clear clean sound at a reasonable sound level..

With luck one of them might not sound too farty..

eg: Vox AC1RV Rhythm Vox Miniature Battery Amp / Fender Mini Twin / Orange Micro crush CR3 /
Marshall Amp MS2 Mini Amp