A previous school used a MS Form and Power Automate to pass orders for approval (it has a built in approval system) this was just by the Head / Deputy (Primary School) as the rules were you had to get approval from the budget holder before submitting but it did send them an email when it was submitted so there was time for them to stop it if they needed too but no reason it couldn't be two stage budget holder, then head. Once approved it send the order to the office to process as usual no paper involved. I wasn't there long enough after it was implemented to know what the feedback was, sorry. Or what audit thought of it.
Power Automate is really powerfully so I'm sure it would be doable but how much support and maintaining it would need long term would be my concern depending on skills and support. Off the shelf might just be easier?