Can I still use a spreadsheet for Making Tax Digital?

Yes, as long as it connects to HMRC through bridging software and the figures move across by a digital link rather than by being retyped.

A digital link is something like a linked cell, a formula, or an import from one program into another. What is not allowed is copying a number out of the spreadsheet and pasting or typing it into something else.

Once a record has gone to HMRC in an update, you must not move it around by copy and paste inside your records either.

So a spreadsheet you already trust can stay. It just needs something bolted on to send from. See gov.uk.