An international student with an F1 student visa is eligible for OPT jobs in USA. A student can work in their field of study till their OPT is valid and then they can apply for H1B as well.
OPT candidates in USA are allowed to work and live in the USA for the duration of 12 months. A candidate cannot travel or work or live in the USA with two statuses.
As H1B and OPT are different, one cannot have both of them and enjoy the benefits.
The risk can be that one of the statuses will be announced void. A student with their current status in OPT resume bank can be notified.
OPT candidates in USA can work and apply for another work permit as well. But they have to change their status with the legal authorities.
Jobs for OPT students have to be changed as their work permit changes, they cannot continue the same. A student cannot travel with two statuses.
After the H1B is approved, a student cannot use OPT job portals or any other OPT resume database for finding a job.
Both statuses are different and a student should be aware of their duration or the starting and ending date from which their status will change.
The legal authorities will not allow a student to do an OPT job in USA after their H1B is approved.
The legal authorities have to be informed. But a candidate should not try to fool them as they are aware of every status.