Assuming a fairly standard CRUD app:
App frontend: Netlify + Vue.js SPA, Tailwind CSS
Backend: REST server in Go, in docker, deployed wherever the hell is easiest. Probably k8s if I don't mind spending $50/mo because I'm super familiar with it and it will scale with me.
DB: Postgres
Cloud provider: GCP
Marketing blog: Hugo + Tailwind CSS
Source control: Github
Issue tracking: Github projects + Github issues
CI/CD: Github actions
Analytics: GA4 (Only if I want to feed Google optimize or Google ads) + Mixpanel
Payments: Stripe
Mail (API and marketing): Sendgrid
I've used a ton of different tools in most of these instances and these just happen to be my favorites for the "standard" use case.
Definitely wouldn't go the fancy SPA serverlerss lambda jamstack microservices route.
Q2: What would be the ideal frontend and backend implementation?