I am researching ways to get from Lisbon to Malaga. Do you suggest train? bus? It can be straight through or with an interim worthwhile stop.

bus or train, pays your money take your choice. Both take a long time both pass locations worth a visit. All routes will involve changing. A train you can get up and walk around. masks will have to be warn at all times on Spanish public transport.

Ryanair and TAP offer non stop flights for about 100-200 EUR/pax (Ryanair starts at 20 EUR wirthout luggage).
You may also travel by train via Badajoz and Madrid (1 1/2 days) or by train and bus via Tavira.
Cheapest connection:
Overnight bus Lisboa dp 22.50. - Malaga ar 8.55; day version: Lisboa dp 7.15 - Sevilla ar 15.10, dp 16.30 - Malaga ar 19.15

Thank you, vanaarle and neckverd - both very helpful. If I were traveling with someone, I would be driving. But this solo old lady does not think driving alone is a good idea. And with your helpful input, I think I shall be flying!

Be very aware of Ryanair's rules on luggage if you choose them. Note their stingy cabin bag sizes and allowances. Also know their check in rules. Read the small print thoroughly or you could end up paying a small fortune for your cheap flight.

Train, whilst long could be relaxing, fun even, and certainly better for the world.