One click order approval or diss-approval Magento 3.2

Description of process The customer is shopping in the front end - selects some items - goes to check out - adds a po or cost centre no. in the usual / standard place and clicks on buy. At this point normally an order confirmation would be send to the customer, all the email addresses loaded in the back end for people who need to take action and process the order would be sent an email and the stock is allocated and removed from available stock. We want to interrupt this process so that when the customer clicks the buy button the following happens - an email gets sent just to the customer stating that their order is pending awaiting approval. Also the stock for this order is allocated. Also an email gets sent similar to the one below to the authorisation manager. At this point the stock is allocated - the customer knows their order is pending and the authorisation manager has this email. If the Authorisation Manager authorises the order - simply by clicking the approve button ( and needs do nothing else ) this actions the order and takes the usual process - the customer received the order confirmation email and all the email addresses loaded in the back end for people who need to take action and process will receive their email to process the order. If the authorisation manager diss-proves the order with one click ( and needs do nothing else ) then the stock for this order is released back into available stock the order is cleared from magento and an email gets sent to the customer with a copy of their failed order simply saying:- Your order has not been approved this time - if you need further information please contact your budget holder. See below the email format: ( ignore the imbedded links in these buttons and the precise layout will be advised )