Which tools can be used to customize in sharepoint online

Which tools can be used to customize in sharepoint online: 

The below Are the Custom Apps or Functions which we will use to re-design or re-develop Customisation's in Cloud once after the Migration from On-premise.

I have used Most of the Fuctions below to re-design On premise Solutions on Cloud.

Add-Ins: A SharePoint Add-in is a self-contained piece of functionality that extends the capabilities of SharePoint websites to solve a well-defined business problem.

SPFx : https://learn.microsoft.com/en-us/sharepoint/dev/spfx/sharepoint-framework-overview

MS Power Platform : Power Automate,Power Apps,Power BI

Use PnP provisioning engine, 

Site Sripts 

Timer Job :  need to be rebuilt using Azure Web Jobs, Power Shell hosted on Azure VM 

Event recievers:  can be rebuilt using Remote Event Receivers hosted in Azure.

InfoPath : Third-Party apps such as Nintex, SPForm,Power Automate,Power Apps can be used to redevelop these forms in SharePoint online.

I hope the above information will help you to resolve the issue, in case of any queries/questions regarding the above mentioned information then please let me know. I would be more than happy to help you as well as resolves your issues, Thank you.