Ideas to upgrade Excel Income and Expense tracker

Sorry for the overly lengthy explanation below but I thought it'll be helpful in getting your ideas:

A few years ago I helped a friend keep track of the income and expenses of his family run guest house (around 10 rooms). The way it works is that his guest house is managed by staff who provide my fiend with regular updates on income and expenses (eg. rooms occupied, income, types and amounts of expenses, referral sources etc).

I built a quick and simple system in Excel with a user form, which the guest house manager uses to log the information. This info gets saved in the same workbook on another sheet. Since my friend lives in another city, the manager then emails the workbook to him on a monthly basis. My friend has a master copy of the same workbook and every time he receives his monthly update, he copies and pastes (appends) the data into his master copy.

The master workbook also has some dashboards built into it which work off the back of some pivots, formulas or the data directly; and provide my friend with key information like monthly profit figures, expense types, most commonly occupied rooms, avg length of stay etc. All worked well but now, since the dataset has increased hugely, the workbook has started crashing. He has asked me to fix it, but I think it's time to change the underlying technology which would better suit the purpose. He doesn't want to approach a professional developer as the profits don't justify the costs. I can develop something but I'm not sure which is the best way to do it:

I'm good with SQL and Excel. My VBA knowledge is intermediate and I've just started learning Python. My initial thoughts are:

I could host a webpage on my friend's machine which his manager can remotely access to fill in information which then gets stored in the SQL server - Again, I've only got very limited knowledge around web page development and hosting. There could be an Excel file (or Tableau once I've learnt it) linked to it and serve as a dashboarding platform. Essentially, instead of storing data in Excel it'll be stored in a SQL database.

If any of you could suggest a better/simpler way of implementing this that'll be greatly appreciated.

Many Thanks