Don't serve your website as PNGs wrapped in a single page application.

Also, if the main reason for blocking bots is to reduce server load, this solution is going to require running multiple browser instances on a server, which will require a lot of resources just to serve normal traffic.

Edit: I should also mention this is going to chew through bandwidth.

Literally anything other than converting websites to images. For example: captchas, proof-of-work captchas, bot detection using techniques such as tls fingerprinting, blacklisting known vps/vpn IPs, etc.

An option can be render each div/element as separate image wrapped in aria markup