Advice on no-code stack for b2b saas web app

I am struggling to decide which platforms to get started with for a new marketing related b2b saas web app idea, I hope somebody can point me in the right direction based on some basic info below.

Essentially the app (based on user input like a search phrase) will need to fetch raw marketing research related data (large search engine keyword or domain lists for example) from a data provider API (JSON), store it in my own DB and then process it, add new fields do some calculations etc and then display that data in a useful way in relatively simple tables and graphs on the front end.

While I am confident at being able to deal with the front end with the platforms that are available, the key part of this type of data analysis app would be the backend processing and each user is likely to be working with alot of data in their account, thousands of records.

What stack might you recommend for something like this? So far I am leaning towards Xeno (seems easiest) or backendless -> Appgyver/Bubble/Appsheet. Looked at airtable and similar platforms but the records limitations can get prohibitive on price for the amount of data needed and fetching data from other API's seemed limited.

Is bubble the best frontend for this kind of thing? Any other deal for web UI? The other popular ones like Appgyver seem geared more towards mobile?

The part that concerns me the most as a non-developer with no DB experience is how difficult it will be to wrap my head around the database design, architecture, and workflow side of things even if I used a good no-code backend platform like Xeno.

I am wondering if I should save myself some headache and hire somebody to at least design the DB and workflow for me and then do everything else myself?

What platforms might be the easiest for a beginner to get started with for this kind of project?

Thanks!