Do I need isolation footers for my components if I'm already using an isolation rack?

Yes.

Ingress Engineering are very effective. Combine with a slate or granite platform and a spring they are even more effective.

not designed for isolation, primarily for side ventilation, however,

what isolation does anyone think two layers of the larger size of these rubber feet provide?

https://www.amazon.com/gp/product/B07PXNTT7K/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1

4 rubber feet on bottom of 2 side panels, 2nd set of 4 on top of 2 side panels, tempered black glass top supported by the top 4 feet.

glass supports top component, up to 150 lbs, i.e. Heavy Amp over Tube Preamp (why I designed it for myself). Lower component isolated from component above.

I think it is unique, others might like it, I will be selling it soon, editing photos now.

IOW, I will be promoting the side ventilation, can description also promote isolation, or just let people think what they think?

how do we post photos here?

No.  If the isolation rack really isolates.  You can only eliminate vibration once.

Careful, reading too much about islolation on forums will result in isolating you from your wallet.

Sent you a PM today.