Assalaamu alaykum dear brother,
There is a difference between working at a company (being employed) and investing in a company.
In so far as employment is concerned, your job description is key to understanding whether your employment and earnings are lawful.
In so far as investing is concerned, the Shariah screening is paramount and a company must pass that.
The reason is, in the former, you are not becoming a shareholder or an owner, in the latter, you are. In the former, you are just a beneficiary, in the latter, you are an “owner”.
So if Amazon failed a Shariah screening test, you would only have entitlement to the capital if you invested.
In terms of bonus paid in stock units, if the initial bonus value was defined in terms of value, you could cash out by liquidating your holdings and keep the amount. The excess/gain must be dispensed in charity.
Allah knows best