A digital template should make a repeated task easier. Start with the user’s task rather than a long list of products you want to sell. A small, useful template is a better experiment than a catalogue built without feedback.
Find the repetitive problem
Ask a few people how they currently organise the task. What do they forget? What takes too long? Which tool do they already use? Look for a need you understand well enough to address simply.
Build one limited prototype
Use original text, formulas and design assets or assets you have permission to use. Make the prototype usable without a long explanation. Include instructions and a realistic example with fictional data.
Test the instructions as well as the design
Ask someone to use the template without live help. Watch where they stop or ask questions. Confusion can come from the instructions, the layout or the choice of features. Improve the part that prevents the task from being completed.
Count support and distribution costs
Creating a file once does not remove the need for support, updates or customer acquisition. Enter any selling fees and relevant costs into the fee and break-even tools. A calculation is a scenario, not evidence that sales will occur.
Decide the next step
Keep the experiment small until you have useful feedback. You may improve the existing template, change the task it serves or stop the project. Record what you learned so the next experiment starts from evidence instead of guesswork.