Image/CSS optimizations when not using QUIC.cloud

From what I understand, if we don’t use QUIC.cloud, we don’t get the page + image optimizations provided by that service. Specifically:

• Viewport images (exclude from lazy load)
• Critical CSS
• Unique CSS
• Image compression/WebP

My question is, can we use alternative plugins/services for these? For example, the “Preload LCP Images” plugin? Or an online critical CSS generator? Or ShortPixel/Optimole for image optimization? Or Autoptimize?

For those of us not using QUIC, it would be helpful to learn some workarounds for the services provided by it.