Magento 2.3.6 P1at least tune up or better upgrade to 2.4.3 P1

I am not a company, so there is no employees. My real job is a drop off commerce scheme, so if a sell something I win a fixed commission of 10% on every sale, normally 99% are off line. But the web site via Google, puts me on the first 10 results, so normally I get a phone call every day, even now that the web site is off line, because of Google Card and Social Media.

I was hacked via phpunit and maybe framework, because I updated from 2.3.6 to 2.3.6-p1, and I forgot to remove the phpunit folder, so the hacker injected XSS and changed permissions in AccountManagement.php. I tried to repair based on Patchman reports everyday since february 15th. But finally I got off line on february 19th, because I deleted the update folder (I guess) and the contents inside var/session. So now I also lose control of CLI php bin/magento.

I am in a shared server, so the resources are limited.

I am looking a fixed price for:

1. Reinstall at least Magento 2.3.6 P1. Or upgrade to 2.4.3 P1 only if is possible not to work with Elastic Search, because I read is not compatible with cPanel in a shared server.
2. Get rid of dev files and third party plugins, that by now I got disabled.
3. Correct an apply better ways to protect the website.

Please let me know if you can help me.